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By James Withers, Dongbo An, Jinhong Zhang

A micro-scale investigation was carried out by applying atomic force microscopy (AFM) to study in situ the adsorption of various collectors, i.e., oleic acid, octanohydroxamic acid (HA), and salicylhydroxamic acid (SHA), on bastnaesite in aqueous solutions. The obtained AFM images show that the surface morphology of bastnaesite changes greatly after it comes into contact with the solutions of the collectors, suggesting that all these collectors can effectively adsorb onto bastnaesite. Increasing temperature can facilitate the adsorption of oleic acid onto bastnaesite. Results from attenuated total reflectance–Fourier transform infrared spectrometry (ATR-FTIR) also show that all of these collectors adsorb strongly onto bastnaesite, with strong absorbance spectra being detected. The ATR-FTIR results confirm those obtained by AFM. In general, hydroxamic acid collectors (HA and SHA) adsorb onto bastnaesite mainly in the form of insoluble metal hydroxamate. This specific adsorption mechanism explains that a high selectivity with a moderate collectivity will be achieved with a hydroxamic acid collector for the flotation of bastnaesite.

By Seppo] [Kreula

Outokumpu Oy has acquired considerable experience with on-stream X-ray fluorescence analyzers and with computer control of flotation processes over several years. It became evident at the outset of this work that a reliable and accurate on-stream analyzer was more than a collection of different pieces of hardware linked together. Extensive work was done to develop an integral analyzer system, beginning with process samples through the spectrometer to report typewriters, recorders and the control computer. To date, over ten Courier-300 analyzer systems based on this development have been installed world-wide, several of which provide the key information for successful computer control systems. Computer control of flotation processes has been under development at the Pyhäsalmi concentrator since 1968. Two different control strategies have been implemented. The copper flotation is controlled by means of a mathematical model and economic criteria, whereas the "evolutionary operation principle" is applied to the zinc flotation. The computer control system installed at' the Vuonos-mine has been developed according to the same guidelines. In order to consolidate this wide experience, a flotation computer control system, Proscon-100, was developed by Outokumpu Oy, and the first system was installed at Kotalahti in 1972. In addition to the technological experience, enough information has also been gathered to illustrate the economical, benefits accruing through the use of these advanced tools of automation.

Jan 1, 1973

By L. M. Gochioco

The U.S. coal industry is under-going dramatic changes to meet the challenges of the keenly competitive fuels market. The application of innovative technologies is needed to improve safety and to increase productivity in order to make coal more competitive as a fuel. As more coal companies shift into capital intensive longwall mining, there is a clear need to invest more in exploration before mine plans are made. Coal seam anomalies may create adverse mining conditions. The early detection of these anomalies could make the longwall mining safer and more productive through improved planning. A standard exploratory drilling program can provide only limited geologic information. The seismic reflection technique can be used to detect coal seam anomalies and is effective in reconnaissance surveying. Recent advances in the quality of coal seismic data have increased the success rate of seismic surveying. Therefore, surface seismic surveys, coupled with selective drilling, will come to play an integral role in coal exploration in the 1990s.

Jan 1, 1990

By Lukas Erkurt, Wolfgang Holzer, Stefan Auderer, Richard Gradnik

SEM/ NATM Tunnelling contracts in Austria and Germany are usually tendered applying unit price contracts. The purpose of this paper is to show how contractual problems are resolved in these countries. The focus will be put on describing the theoretical approach, several case studies will show how contractual problems were dealt with on site.

Jun 23, 2024

By V. Duddempudi, B. Goertz, J. Brune, G. Bogin, F. S. Barreto

"INTRODUCTION In designing a new pneumatic Dust Sampling Device (DSD) for coal mines, it was essential to analyze the air and particle flow inside the device in detail using Computational Fluid Dynamics (CFD) modeling. Several CFD models were developed to simulate the air and dust flow and sample collecting process of the DSD. These CFD models were developed to assist in the design of the DSD instrument prototypes for laboratory testing. Nozzle and injection parameters such as geometry, air velocity and pressure, were varied across a wide range to obtain the optimal settings to accurately simulate the fluid dynamics of the multi-phase flow within the DSD. Accordingly, these parameters were used as a guide for the design of the DSD and to verify the dust scouring dynamics, which is designed to represent the dust entrainment during an actual methane or coal dust explosion. BACKGROUND The 2010 explosion at the Upper Big Branch mine has demonstrated the destructive violence of a coal dust explosion. A major contributing factor for this disaster was that the mine operators did not have a reliable, direct-reading method to collect mine dust and determine inert content and combustibility. This led to the development of a new prototype handheld, pneumatic mine dust sampling device (DSD), which blows a puff of air and entrains the mine dust by mimicking the entrainment process during a mine explosion. A computational Fluid Dynamics (CFD) model is used to analyze the air and dust flow inside the DSD. The objective of the CFD modeling effort is to find the optimum design of the DSD prototype, nozzle orientation, air pressure and pulse length by analyzing and varying these parameters so that the scouring action collects a valid, representative and repeatable mine dust sample. CFD MODEL DESIGN Figure 1 shows a wireframe image of the DSD which is utilized in the setup of the CFD model. The DSD has a triangular cross section and is 10 cm wide. Two nozzles with cross-sectional dimension of 2.8 cm by 0.25 cm act as inlets at the narrow end of the triangular cross section. The CFD model includes a reference plane 6 cm away from the nozzle to measure the quantity of dust collected. The geometry shown in Figure 1 was created for the model and it matches with the design of the actual device shown in the figure 2. Symmetry, along the plane X-Y through the center of the device, is used to reduce the number of computational cells in the CFD model. Figure 2 shows the prototype device used for experimental testing. CFD MODEL SETUP Figure 3 shows a hexahedral mesh with a cell size of 0.8 mm and the total number of cells is around 650,000. The ANSYS Fluent® pressure based solver with a transient case was used with a total duration of 40 ms. The 40 ms simulation time is based on experimental measurements to capture the injection of air and initial scouring of dust."

Jan 1, 2016

By Richard D. Begley

This paper will present the results of an analysis of several abandoned coal mine projects and includes field data for over a dozen different reclamation projects recently completed in the state of West . Virginia. The analysis was performed with the objective of summarizing and or classification of the environmental consequences with reference to the characteristics of the mining facilities (surface, underground, etc.). The analysis also addressed the itemized cost of remediation with respect to procedures, environmental concerns and time. The results of the analysis are that each abandoned coal mine site in West Virginia have/had many unique features and in most cases include a combination of environmental concerns that complicate comparisons. The study also revealed that the abandoned mine land program for mines abandoned prior to 1977 that is being financed by a tax on the production of coal, has produced many benefits for the state of West Virginia. This grant program administered by the Office of Surface Mining, has resulted in a high quality methodology of remediation that has been successful for many years in greatly minimizing and/or eliminating environmental concerns from abandoned coal mines.

Jan 1, 1997

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay

Accurately estimating load distributions and ground responses around underground openings plays a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the mining-induced loads, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses, both empirical and numerical. In this study, the numerical modeling approach recently developed at West Virginia University, which is based on the modeling approach developed by the National Institute for Occupational Safety and Health (NIOSH), is investigated using the finite difference software FLAC3D. The model includes the longwall panels, the adjacent chain pillar systems, and the different stratigraphic layers of the overburden. Using the 3D model, changes in loading conditions and deformations on the areas of interest, induced by an approaching longwall face, can be examined. This paper details the 3D modeling of a longwall panel utilizing this approach, and the verification of the results against field observations. The studied panel was 360 m wide with a 3-entry chain pillar system and about a 160-m average overburden depth around the studied area. The overburden strata consist of alternating layers of shale, sandstone, and limestone. The FLAC3D results were compared against field measurements from the mine site. The stress change values measured in the chain pillars were comparable with the modeling results. The model also replicated the surface subsidence profile obtained from field measurements fairly well. Overall, the 3D modeling approach was found to be successful for the case study longwall panel.

Sep 23, 2020

By Ryan C. Stephan, Zach Agioutantis, Christopher Mark

During the past 15 years, roof fall rates have fallen dramatically in US coal mines, particularly in regions where the roof is weakest. The remarkable reduction in the number of roof falls has been accomplished with more effective roof support systems. The purpose of this paper is to present a design methodology that builds on and quantifies the basic roof support concepts that have been successful in the USA. The methodology starts by defining three modes of roof support, based on the roof strength relative to the stress level: (1) suspension, where roof bolts mainly provide skin control for strong roof; (2) beam building, where moderate strength roof can be supported by roof bolts alone; and (3) supplemental support for weak roof. Next, a large database of roof fall histories at a number of mines is used to define the approximate boundaries of these three regimes based on the coal mine roof rating and the depth of cover. Finally, guidelines are presented for site-specific design of support systems within each regime. The new computer package, analysis of mine roof support (AMRS), implements the design methodology.

Sep 29, 2020

By G. Papantonopoulos

Natural stones are extensively used for construction purposes since the dawn of human civilization, due to their unique aesthetical and technical characteristics. Their production and consumption has been continuously increasing over the past twenty years worldwide at an annual rate of 8.8%. European countries lead the race of per capita consumption, with Switzerland being in the first place with a consumption of 144.7 m2 per hundred inhabitants followed by Greece, Spain, Portugal, Belgium and Italy. On the other hand, during the period 2001-2002 the generated stone wastes were 110 million tones according to EU data, from which only about 5 million tones were recycled or re-used mainly in the construction industry. These stone wastes the non-natural wastes such as oils or chemicals coming from the equipment and machinery employed for stone extraction and processing, are disposed in the environment, posing serious environmental threat. To achieve sustainable development of the stone sector appropriate methods that will prevent or reduce waste generation and disposal have to be identified and applied. In this work an extensive study of the stone waste management techniques applied in Europe is carried out, in order to identify the Best Available Techniques (BAT) that can be used according to the type of generated wastes and the waste management hierarchy: Waste minimisation, Re-use, Recycling and Disposal. The identification of BAT was performed based on 14 Sustainable Development Indicators (SDI), which were grouped into three categories: environmental, economic and social. The developed final list of BAT includes waste minimisation techniques, eco-management schemes, in-situ treatment and appropriate storage and selection.

Jan 1, 2007

By Stephen Njoloma, Ivan Hee, Ravi Jain, Mina Shinouda

"INTRODUCTION DC Water’s First Street Tunnel (FST) is comprised of a collaborative effort between DC Water, DC Water’s Project Consultants Organization (PCO) led by Greeley & Hansen and McMillen Jacobs Associates and the design-build team of Skanska, Jay Dee, and Parsons Brinckerhoff. The fast-track project includes elements that were designed by the PCO and released for construction by DC Water prior to Notice to Proceed (NTP) and elements designed by the Design-Builder from 30% to released for construction after NTP. This required effective communication and technical coordination for integrated engineering and efficient construction. The project, constructed in an urban residential neighborhood, included innovative construction methods such as multiple location ground freezing, utilizing a centralized freeze plant, to minimize community impact. The means and methods chosen for cast-in-place shaft linings, precast segmental tunnel lining, microtunneling, sequential excavation method (SEM) adits and near surface elements reflected the immediate and sensitive surroundings, which varied by construction staging area (CSA). Technical aspects of the project, relative to the evolution from pre-bid to construction documents, are discussed along with modified designs to suit means and methods. SCOPE OF WORK In 2012, four major storm events swept through the District of Columbia and hit the Northeast Boundary sewer shed particularly hard with the neighborhood experiencing severe flooding. The extreme nature of the flooding, the damage to private property, and the health risks associated with exposure to sewage led to a multi-agency response and community calls for answers and action. The Mayor assembled a Task Force to evaluate a range of potential actions to address combined sewer flooding including engineering, regulatory, code revision, and management improvements. The Northeast Boundary Neighborhood Protection Project was the outcome of the Mayor’s Task Force; it is a three-step infrastructure initiative designed to offload the undersized sections of the existing collection system that serves the Northeast Boundary drainage area by implementing the McMillan Stormwater Storage Project, First Street Tunnel Project and the future Northeast Boundary Tunnel Project. Until the Northeast Boundary Tunnel Project is completed, the First Street Tunnel Project will add 8 million gallons of combined temporary sewer storage in a new tunnel under First Street NW to relieve undersized sewers that traverse the Bloomingdale neighborhood."

Jan 1, 2016

By L. G. Hagenbuch

Several factors need to come together in creating an integrate mining equipment dispatching system. At the hub of these factors ace the central dispatching formulas. This paper details the development of these central dispatching formulas and explores the combining of these formulas with other elements to create an integrated dispatching decision. WHY DISPATCHING? Truck dispatching implies and in reality should equate to mine equipment efficiency. Good truck dispatching will yield good mine equipment efficiency while poor truck dispatching will yield the alternative. Truck dispatching can either be automated through a computerized, process or it can be manual. Every mine with haul trucks has a truck dispatching system whether it is recognized or not. Even a system wherein the hauler operators determine where they are going for their next load is a truck dispatching system.

Jan 1, 1987

By Melvin A. Jennings

Even though the title of this paper is quite long, the ideas presented herein are very simple. In fact, it occurs to me to be somewhat humble about coming before such a distinguished group with such a simple presentation. However, the application of these ideas has proven useful in at least two copper flotation plants. The purpose in presenting this paper is to inspire some interest in the great stores of data chat the Mining Industry often accumulates without making any attempt at analysis. Unfortunately, many milling engineers rely rather heavily on percent recovery as a strict measure of a concentrator's relative performance. The fallacy of this reasoning is not difficult to see since, by definition, percent recovery is a function of feed assay, tails; and concentrate grade. If copper tailing is constant, and it very nearly is for a strictly sulfide copper ore, percent recovery must fluctuate almost directly to the feed assay. The point that I wish to make here is that it is very seldom justified to compare the percent recovery figure from one period of time to another without considering the difference in feed assay. The problem of comparing results is even further complicated when the ores are of mixed oxide and sulfide mineralogy.

Jan 1, 1978

By F. Dingwu

The latest technology and novel equipments in kaolin processing industry in China are described in this paper. Some typical experimental results are presented, which include laboratory-, pilot-or commercial-scale tests. The characteristics of kaolin processing technology are summarized, and the developing trends are indicated.

Jan 1, 1995

By G. Zhu

Bulk and differential laboratory flotation tests have been carried out using a synthetic mixture of chalcopyrite and molybdenum ore. In addition to boiling and roasting, six different depressants are tested so that the best conditions of separation can be identified. These reagents include sodium cyanide with and without zinc sulfate, potassium ferrocyanide, sodium hydrosulfide, arsenic Noke's reagent, and sodium sulfide. The data indicate that most of these reagents are effective chalcopyrite depressants. However, sodium hydrosul fide can be used preferably if economic, operational, and environmental factors are taken into consideration.

Jan 1, 1983

By Susan G. Bilhorn

A number of studies have been conducted in active and inactive mine environments using continuous monitoring and data acquisition systems to detect various parameters. In addition to the information obtained for research purposes, these monitoring systems can provide a means to remotely collect required information (such as radon daughter concentrations and air velocity) and control various conditions (such as fan operation and air door position) in numerous working sections of an active mine. Selection of detector locations and placement, which are critical to obtain the information and control desired while not inhibiting mine operations and influencing the detector readings, are covered in this paper.

Jan 1, 1984

By A. Noble

For the past 30 years, process flowsheet design has been accomplished largely through modeling and simulation. This approach provides circuit designers the freedom to test various separation approaches while minimizing physical and human resource requirements. The Limn® software provides a unique approach to process simulation, through a Microsoft Excel interface. While the software comes with standard process models for numerous unit operations, the Excel calculation environment and the accompanying VBA platform provide a convenient interface for custom model integration, even for non-experienced programmers. This feature is especially useful for university students in introductory process modeling and simulation-assisted flowsheet design courses as well as experienced practitioners with proprietary process models. This paper shows how the Limn® software may be used to solve basic process engineering problems as well as more comprehensive circuit design challenges. Industrial examples as well as opportunities for training and education are presented.

Feb 23, 2014

By Arthur E. Belton

Ever since the industrial Revolution both major and small companies have put much emphasis on the use of incentives to compensate top management for extra effort and extra skill. For many years industries have also provided hourly rate employees with incentive plans. More recently incentive plans have been extended to include the "front line" supervisors. Many companies have what are called Christmas bonus or profit-sharing plans. The incentives for foremen in mining, which we shall discuss, differ from such bonus plans in that the incentives are paid on a definite measured performance for each individual, and thus directly reflect his effort and skill. What is the objective for paying incentives? The objective for any part of an industrial Engineering Program is to increase productivity and reduce unit cost. The unit cost must include the entire cost of the program. From what base do we start an incentive plan? One should think of art incentive program as the top rung of the Industrial Engineering ladder. Therefore, a company must take several steps before reaching this top rung. The following steps are necessary:

Jan 1, 1960

By John R. Riede

The use of radioactive gages in beneficiation plants is relatively new However, enough applications have been made so that it is now possible to positively state that these gages have definitely progressed from a laboratory device to a very rugged and reliable on stream process measuring instrument. Gamma Ray Gages of the type presently being used in the beneficiation industry consist of three basic components: (1) A source of radiation (2) A radiation detector (3) An electronic amplifier The source is usually a radioisotope such as cesium-137, or cobalt-60. This source, adequately protected and ruggedly mounted, is most commonly placed on one side of a pipe or vessel. The radiation detector is then mounted on the opposite side, Since the absorption of gamma radiation as it passes through various materials is a function of the density of the material, the change in radiation measured by the detector is proportional to the change in specific gravity of the product in the pipe or vessel. One popular type of detector in use today is a cell which converts radioactive energy directly into electrical energy1. This electrical energy, when amplified, presents a usable output for metering and control devices. There are, of course, many other components which are part of a working gamma gage installation, such as zero compensators, lead shielding, mounting brackets, equivalent absorbers, etc.

Jan 1, 1958

By E. H. Smith

St. Joe Minerals Corp., a subsidiary of Fluor Corp., treats high-grade gold, silver, and copper ore at its El Indio plant at an altitude of 4 km in the Chilean Andes. The ore is complex, being a mixture of massive pyrite-enargite and quartz, both containing very fine gold and silver. Treatment produces a copper flotation concentrate containing high levels of gold, silver, and arsenic, and also dore bullion. Part of the flotation concentrate is roasted to remove the arsenic content, and arsenic trioxide is collected as a by-product.

Jan 1, 1987

By R. Todd Swinderman

Variations in designs between belt cleaner systems are so wide that it is impractical to establish a dimensional stan- dard. The number of variables that affect the efficiency of belt cleaners is too great to assume a required number or style of cleaners for broad classifications of bulk solids or typical applications. The amount of carryback remaining on the belt is more dependent upon the characteristics of the bulk solid and the physical parameters of the conveyor system than it is on tonnage of material conveyed. Therefore, a performance-based standard is proposed. Three levels of cleaning performance are proposed: • Level I cleaning is general specified when concerns about carryback are not critical. Cleaning systems normally associated with achieving a Level I performance are single or double cleaner systems with one-piece blades undergoing poor to average maintenance. Frequent cleaning of the carryback that falls from the return run will likely be required. • Level II cleaning is generally specified when carry- back is of concern but does not create a safety or environmental problem. Cleaning systems normally associated with Level I1 performance are multiple cleaner systems with segmented blades undergoing the manufacturer's specified maintenance. Regular but infrequent cleaning of the carryback that falls from the return run will likely be required. • Level III cleaning is generally specified when con- cerns about carryback are critical. Concerns range from safety to environmental to product contamination. Cleaning systems normally associated with achieving a Level 111 performance are multiple cleaner systems in conjunction with at least one low- volume water spray. Scheduled inspection and the manufacturer's specified maintenance would have to be performed to maintain a high level of cleaning performance. Difficult-to-clean bulk materials may require the use of a washbox system with multiple cleaners using a combination of low-volume eater sprays to lubricate the cleaners and high-volume sprays to keep the washbox and discharge piping freely flowing. Further addition of a water and sludge recycling system reduces the amount of water that ends up in the product to a negligible amount. Very infrequent cleaning of the carryback that falls from the return run will be required. PURPOSE The purpose of this proposal is to propose a standard method for specifying belt cleaner systems based on user expectations and equipment performance over time. DEFINITION In bulk solids handling by conveyor belt, carryback is the material that adheres to the belt after the belt discharges its cargo. PROPOSED STANDARD Required Basic Good Practices There are a number of basic design and operating principles that are good practice for the selection, installation, and maintenance of belt cleaning systems on conveyors in order to achieve "standard belt cleaning performance over time. 1. The Belt Cleaning System shall be designed to meet the performance requirements based on the worst operating conditions and worst bulk solids proper- ties that are expected. 2. Each conveyor discharge point shall be designed to readily accept the manufacturer's recommended minimum number of belt cleaners. In addition, the discharge chute shall be designed to accept, with minor modifications, at least one additional cleaner if it is required.

Jan 1, 2004