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By T. H. Eyde

Natural Zeolites are a less expensive and in certain applications a superior alternative to organic ion exchange resins. Mining and metallurgical waste streams are difficult to treat because the effluents which contain potentially valuable heavy metals such as copper, lead, and silver are often highly acidic and contain significant quantities of suspended solids. Under rigorous operational conditions, certain natural zeolites can remove the metals, which if desired can be recovered by either elution or conventional smelting techniques. There are significant differences in cation exchange rate, selectivity and capacity as well as resistance to either high or low pH, blocking cations and tolerance to elevated or depressed temperature and pressure not only between different zeolite minerals but between the same mineral from different deposits. Applying natural zeolites to the treatment of mining and metallurgical waste streams depends on matching the specific zeolite to the effluent by characterization of the zeolite minerals.

Jan 1, 1994

By Ronald M. Fedrick

The microtunneling project for the State of Hawaii's Natural Energy Laboratory (NELH) facility in Kona, Hawaii, was awarded to Nova Group Inc., Napa, California. Nova has developed both microtunnel and deep pile cofferdam experience. Both of which would be required for this project. The project was designed by Makai Ocean Engineering of Honolulu as a continuation of the Ocean Thermal Energy Project (OTEC). The world's first OTEC plant has been successfully operational at NELH since 1982 netting approx 50 kw of usable electric power from a gross generation of 210 kw. A second plant designed to draw 39°F cold water from 3,000 ft below sea level and produce a gross output of 1 mw with a net 500 kw of usable power required 2 - 54 in. finished diameter pipelines. An ongoing problem with earlier offshore pipelines has been the damage to the near-shore pipes within the surf zone. The necessity for a deeper connection between the land based pipe and submerged sea pipeline was obvious. Earlier pipelines had been drilled and shot through the shoreline. This process was only practical at shallow depths. Makai Ocean Engineering and the NELH scientists looked at different methods to get the pipeline through the shoreline at a depth of 80 ft below sea level. Initially, the direction drilling method was proposed as the most potentially practical method. A contract was awarded and various attempts were made to complete a successful

Jan 1, 1995

By Spencer R. Titley

Nearly three decades of intense research, corresponding with a period of unparalleled discovery and the advent of scientific advances and hypotheses of ore formation, has resulted in a great body process-focused research concerning how ore deposits form. The development of process models and their application has proceeded more or less in step. Discoveries have been made in mineralized regions such as provinces and districts but generally without a comparably developed understanding of why provinces and ore bodies exist and, except in general terms, where ore deposits are within districts and regions. The process of discovery is still referred to as search and exploration budgets are heavily weighted toward exploration drilling.

Jan 1, 1995

By Jamal Rostami, Wei Hu

Efficient performance of EPB TBMs in clayey ground is primarily dominated by the flow capability of the excavated muck in the cutterhead and screw conveyor. Currently, Consistency Index approach is used to evaluate clay clogging potential, but it does not include the effects of surcharge pressure on clay behavior. In this paper, a macro-scale soil rheometer is introduced to assess the clogging potential under various water content and surcharge loading conditions. The results show that, in addition to water content, surcharge pressure has clear impact on clay clogging too. In practice, Consistency Index chart can be refined to incorporate the impact of face pressure to better simulate the EPB tunneling conditions.

Jun 13, 2021

By S. Tan

A computer-oriented systems simulator (CMHS) has been developed for analysis of continuous materials handling systems. Special emphasis has been placed in the model on several features which are unique to these systems. These features include periodic pattern of material arrival from several sources, several types of material to be transferred, material dispatch processes, intermediate storage capacities, and multiple material destinations. Both the deterministic factors of the continuous material handling system such as the physical decomposition of the system and the scheme and schedule of its operation and the stochastic factors such as variations of material arrival, material pattern on the conveyor, and avail-abilities of the system elements are considered in the simulator.

Jan 1, 1988

By H. H. Murray

New and improved benefication techniques are available to allow the production of clay minerals of exceptionally high purity. This is particularly true for kaolins and smectites. Wet processing techniques including particle size separation, high intensity magnetic separation, chemical leaching, flotation, and selective flocculation are described and results and applications are discussed. The blending of clay minerals with other minerals provide opportunites to make special ceramic materials such as cordierite and other minerals which have very special ceramic properties including low heat expansion, high fired strength, low absorption, and other desired qualities.

Jan 1, 1989

Optimal gold recoveries largely depend on efficient liberation of the gold or gold-bearing minerals as well as on maximum access for the lixiviant. Thus, crushing and grinding may become the most costly part of gold ore processing. It may, in fact, represent 50% to 70% of a plant's operating costs (Michaelis, 1989). The increasing significance of refractory gold will require even more cost-efficient comminution of ultrafine sulfides and/or native gold. Transitional ore zones with semi refractory gold may respond to direct leaching if better particle fracturing is being achieved (Baum, 1991, 1993a). Many oxide ores have been left in the ground because they were unsuitable for heap leaching since conventional comminution could not facilitate economic gold extraction. Also, the costs of conventional bal1 mill operations did not permit the recovery of gold from many ultrafine, low-grade refractory ores. As shown by Marsden et al. (1993), the trend to treat ores with progressively lower grades will involve power-and leach-efficient grinding applications. Our current laboratory work shows that high-pressure grinding roll (HPGR) Polycom grinding may enable many mining companies to add large amounts of these "non-leachable" ores to their current heap or mill leach feeds. This finding may dramatically change the economics of many oxide gold ore operations and may add significant reserves to ores amenable to direct cyanidation.

Jan 1, 1994

By V. Srivastava, T. Ghosh

"Modeling and Simulation of SAG Mill has been widely used in design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. This paper attempts to characterize mill contents by solving Whiten’s first order contents based model in Matlab/Simulink environment. The parameters in the model such as breakage rate (S), discharge rate (D) and appearance function (A) were estimated utilizing process and design data collected from a gold mine operating in Alaska coupled with nonlinear parameter estimation scheme. This model is then utilized to predict dynamic response of other key operational variables such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated utilizing dynamic response data from the plant to encompass operational characteristics of SAG Mill behavior. Keywords: SAG Mill, Dynamic Modeling, Simulation, Nonlinear Parameter Estimation. INTRODUCTION Grinding in mineral industry is one the most important steps in the process of size reduction and plays a crucial role in determining the overall economics of the milling plant. Much of the efforts focused on improving the process efficiency using modeling and simulation have been practiced by researcher and engineers. However, up till now these models were simulated under steady state approximation because of their complex nature and difficulty in programming them in a dynamic framework. Steady state simulations have been successfully utilized in circuit designing, capacity planning and pre-flowsheet optimization. The maturity in steady state models is because of its applicability and regular use in steady state simulation packages such as JKSimMet, Limn, ModSim, etc. With the advent of equipment such as SAG and AG mill has been a recent shift in the simulating these models using dynamic approach. Because of the economic benefits of these devices and ability to act both as a primary grinding device and as secondary or tertiary crushing device they have gained a large popularity and are now universal to any milling plant. However, these device poses a real challenge to engineers and researchers in terms of operation and control. The major reason attributed to problems faced is because the ore constitutes the major portion of the charge in these devices when compared to ball and rod mill. This rock charge is subjected to disturbance such as changes in feed size distribution and ore hardness which results in unstable operation and frequent mill stoppages. One way to prevent this is to measure and control these external variables, however, lack of available instrumentation and unavailability of sensors to measure these variables has foiled the understanding of complete process occurring inside the mill thereby, inhibiting development of proper control system."

Jan 1, 2017

By A. Anani, K. Awuah-Offei

"Accounting for changing duty cycles in equipment matching maximizes equipment utilization and productivity. The objective of this study is to investigate if the optimal number of shuttle cars for a particular panel width is optimal in different segments of the panel. In this study, discrete event simulation (DES) is used to determine the optimal number of cars that maximizes productivity in each segment. Data from a real-life mine is used to validate the model. The study shows that the optimal number of cars for the entire panel may not be optimal for some of the defined segments. INTRODUCTION Fleet optimization is important for efficient mine management. Deploying the optimal fleet minimizes the capital and operating expenditure for particular operating conditions and production targets. In an operating mine, with an already existing fleet, deploying the optimal fleet maximizes productivity or minimizes production cost with the available resources. Hence, a lot of research has focused on how to determine the optimal fleet size for a mining operation, given particular operating conditions. Mine managers and engineers have successfully used discrete event simulation (DES) to determine the optimal fleet size in mines (Michalakopoulos, Roumpos, Galetakis, & Panagiotou, 2015; Awuah-Offei, Osei, & Askari-Nasab, 2011; Ben-Awuah, Kalantari, Pourrahimian, & Askari-Nasab, 2010; Govinda Raj, Vardhan, & Rao, 2009; Yuriy & Vayenas, 2008; Kwame Awuah-Offei, Temeng, & Al-Hassan, 2003). In most cases, the published work on this topic involves determining the number of hauling units to be matched to a loading unit. Many of these examples involve truck-shovel optimization. There are, however, some underground mining examples. For instance, we recently concluded work that involves fleet optimization in underground room and pillar (R&P) coal mining (Awuah-Offei & Anani, 2015). Generally, when DES is used in fleet optimization it involves three steps: (1) Build a valid model of the mining system capable of predicting the required outputs with varying fleet composition; (2) Design and conduct experiments that vary the fleet composition across all feasible options; and (3) Determine the optimal fleet based on the results of the simulation experiments. A major decision in the first step is which outputs should be modeled. Some examples in the literature include productivity, unit cost, loader utilization, queue length, and hauler waiting times (Awuah-Offei et al., 2011; Govinda Raj et al., 2009; Kwame Awuah-Offei et al., 2003). Often, more than one of these outputs are simulated and considered as the objective function of the optimization."

Jan 1, 2016

By Robinson Leon-Diaz, Alberto Jaen-Toribio, Raymond Blanchard, Mike Deevy, Miguel Fuentes-Llanos

"Tunnels designed to NFPA 502 are required to withstand the RWS time-temperature curve, more specifically prevent progressive spalling and loss of strength of steel reinforcement. Fire boards or spray-on layers can be effective, however, these solutions have capital and whole-life cost implications. The use of “fire resistant” concrete based on a suitable aggregate with polypropylene fibers has also increased in recent years. This article presents a new methodology for thermal and structural analysis of segmentally lined tunnels, which permits the analysis of project specific fire curves and an assessment of different fire protection strategies. The effectiveness of fire boards is assessed along with whether “fire resistant” concrete alone is a viable means of achieving the required protection. Finally, since NFPA 502 recommends water-based fixed fire-fighting systems for Category C and D tunnels, we discuss the question of how a fixed fire-fighting system should be addressed within the structural design. INTRODUCTION Protecting road tunnels from structural damage and collapse is a key requirement for both life safety and business continuity. Where road tunnels are part of key highway corridors, protecting business continuity is a high priority for owners, operators and the Authority Having Jurisdiction. For existing tunnels, compliance with NFPA 502 may require upgrades with either passive fire protection and/or water-based fixed firefighting systems. For new tunnels, compliance with NFPA 502 requires a combination of good practice in design and fire testing. A water-based fixed firefighting system is a Conditionally Mandatory Requirement1 for Class C and D tunnels, i.e. all tunnels greater than 300m and 1000m long respectively. The basis for fire safety design of new tunnels and assessment of existing tunnels is the worst-case fire scenario. A number of factors, including but not limited to the following, influence this design fire scenario:"

Jan 1, 2016

By B. P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using carbonate solutions. The objective of the present study was to increase the absorption rate of CO2 into the carbonate solution without reducing the absorption capacity of the solution. This approach used a polypropylene glycol methyl ether (PPGME) as a surfactant to chemically alter the gas bubble size. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations of 0, 0.12, 0.24, 0.36 and 0.48 g/L. Results showed that as the concentration of surfactant increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 mmol/min CO2 at 0 g/L PPGME to 3.92 mmol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in absorption capacity of the solution.

By Nic Arrieta

The Arimetco White Cliff Diatomite operation near Tucson, Arizona will be discussed and reviewed across the spectrum of geology, mineralogy, mining, processing and product attributes and market applications. Unique for the operation are the type, quality and the extent of the reserves and several product characteristics of the diatomite.

Jan 1, 1996

By Malcolm T. Wane

The subject matter of this paper, "Applied Rock Mechanics?," has its genesis in a recent field trip taken by the author. A more or less standard question asked at the mines visited was "How are you using the principles of Rock Mechanics to assist you in maintaining an efficient, safe, and competitive mining operation?" The question was couched in a number of different forms, but the intent was to determine whether or not a general theory based on reason and the scientific method was applied or whether the alternatives of tradition, intuition, ?common sense', revelation, ?shotgun methods' or authoritarianism were invoked. Perhaps two responses to this query will be illustrative of the general nature of the replies. At operation XYZ an extension to the known ore body has been found. The extension is of large enough size and grade that a mining scheme using load-haul-damp techniques is envisaged. Since this represents a departure from the present mining scheme, questions have arisen regarding pillar sizes, room and entry sizes and possible support requirements. A task force has been set up to expeditiously plan for these things and write the necessary specifications and requirements. The fundamental question was posed to members of this group.

Jan 1, 1971

By P. Songfack

In this work, the slurry flow in the ball mill is solved with Navier-Stokes' equations and the marker and cell technique (MAC), which tracks the fluid-free surface. Considering different planes in the radial and axial directions, this numerical approach leads to the direct calculation of the slurry velocity profile, mill holdup, and volumetric flow in the ball charge and pool. The MAC technique takes as input, the results of a direct three-dimensional simulation of the motion of grinding media, and in turn, provides a detailed knowledge of the hydrodynamics of slurry flow through the porous structure of ball load. This technique is a new approach to the mass transport problem that overcomes the limitations of indirect studies such as residence time analysis and holdup measurements.

Jan 1, 1994

By Alexandra P. Wright

A vital aspect of environmental impact assessment for surface mining operations is the determination of potential effects on water resources. This topic has been the subject of much recent concern, controversy and legislation. As increasing data become available regarding the types of hydrologic effects that may be anticipated, methods for safe guarding our water resources can be refined. In view of our current energy situation, the need to develop coal re- sources in a timely and economic manner is apparent. The challenge to the mining industry is to develop these resources in a manner that is also compatible with the beneficial use of water resources in mining regions. For this reason, thorough evaluation of the hydrology of potential mining areas in consideration of proposed mining processes and relevant legal criteria is essential. While pre-mining hydrologic investigations often suggest generalized potential effects, a more reliable method for evaluating specific potential effects is to establish and maintain a hydrologic monitoring program. Such a program must be carefully designed to suit the specific project and its location. This paper describes an approach for selection of criteria for designing a monitoring program for a proposed coal surface mining operation and gasification plant in southwest North Dakota. Woodward-Clyde Consultants (WCC), recently prepared an environ- mental impact report for the ANG Coal Gasification Company (ANG), a subsidiary of the American Natural Gas Company. The mining will be carried out by The North American Coal Corporation (NACCO). Preparation of the report provided the opportunity for the development of a sensitive and economical monitoring program which would function as a baseline hydrological data gathering network as well as act an an early detection system for hydrologic effects of the proposed mining.

Jan 1, 1975

By A. E. Koski

This paper will review recent developments in the area of mine planning at the Empire Mine. It illustrates how one of the largest iron mines in North America has adapted computerized mine planning to meet the unique requirements of their mining operation.

Jan 1, 1994

By Klein E., Kinscher J., Lizeur A., De Santis F., Lhoumaud E.

Seismic repeaters are rarely observed phenomena in underground mines. However, recent studies in Garpenberg mine (Sweden) have demonstrated that seismic repeaters and multiplets may represent significant portion of the total number of microseismic events (> 80 %) related to excavation operations. Detailed seismic analysis, involving template matching, multiplet clustering, double-difference relocation, source parameter and mechanism estimation, and interevent time analysis, suggest that seismic repeaters represent brittle frictional parts (asperity) of creeping, planar shaped, pre-exiting structures of several meters length. It is furthermore suggested that seismic repeater occur preferentially in weak rock-mass materials (e.g. talc) associated with strengthening friction behaviors. These results may imply that postblast related stress redistribution may be governed by “silent” aseismic movements in preferentially weak rock mass materials, what questions the reliability and performance of seismic monitoring to survey stress evolution during excavation operations. However, once the seismic and aseismic coupling processes and the geological nature linked to repeater occurrences are better understood, their detailed monitoring bears also opportunities to survey and quantify aseismic post-blast stress transfer. Here we present ongoing investigations on repeater occurrences aiming at better understating on their geological and geomechanical origin. Furthermore, we try to develop advanced monitoring tools helping to quantify aseismic slip and to provide criteria for seismic hazard as asperity density and the related potential to generate larger dynamic rupture zones. For this respect a local monitoring network has been set up close to certain repeater target families. Furthermore, geological well log drilling throughout repeater occurrences as well as geotechnical strain measurements (e.g. extensometer, optical fiber etc.) are currently conducted to provide crucial information on the geological nature of repeater and to quantify and characterize background creep induced from excavation.

Apr 26, 2022

By R. K. Mehta

An electrochemical coal oxidation model involving heterogeneous kinetics is presented. This model was tested by collecting current transient data on three coals assaying different ash content under varying operating conditions such as particle size, temperature, and % solids. In all cases, the model fitted the data very satisfactorily. Three intrinsic rate constants, namely mass transfer coefficient of Fe(II) Ions diffusing from solution to the anode (kma), mass transfer coefficient of Fe(II) Ions diffusing from solution to the coal surface (kmc), and chemical rate constant for coal oxidation with respect to Fe(III) at coal surface (k), were calculated. It was interesting to note that in this system, the mass transfer at anode was as important as the chemical reaction at the coal surface. The validity of this model was further demonstrated through a comparison of the activation energy of coal oxidation: firstly, by utilizing calculated chemical rate constant and assuming Arrhenius' type of relationship: secondly, by utilizing conventional approach using limiting current values. The comparison revealed that agreement was quite close. This kinetic analysis is useful because such a model can be used in predicting the intrinsic rate constants so that the relative importance of mass transport can be rationally analyzed.

Jan 1, 1991

By E. A. Rychkun

Mining and environmental objectives have traditionally been in conflict. This conflict reflects a delicate balance between the need to spend money to protect the environment, and the need to save money by extracting minerals efficiently. In an increasing number of cases, profit margins diminish rapidly with new environmental regulations and reactionary measures. Forced cleanups and increasing restrictions are unwelcome expensive processes. A practical solution lies in planning rather than reacting. This requires the ability to precisely quantify and qualify environmentally sensitive problems by providing effective engineering tools to model, visualize and analyze subsurface conditions. Prevention of environmental conflicts, and effective cost control are both rooted in the mining company's ability to construct accurate models, monitor changes, assess contamination risks and to design effective remediation plan. This paper presents a case study where these issues are addresses through the application of a new and innovative technology.

Jan 1, 1993

By J. Mastoris

The problem of defining the optimum final limits of an open pit mine has challenged the mining industry for the last three decades, mainly due to the great number of variables involved and the sheer computational effort required in real life applications. An actual lignite deposit is used in this study in order to introduce and apply a methodology to be used as a basis for surface mine design optimization. A geologic reserves model of the deposit is first developed with the use of an integrated geostatistical modeling package. The model is transformed into an economic one through the use of flexible objective function formulation(s). The optimization of the final open pit limits is then enabled with the use of a competent, commercial optimizer, and comparative sensitivity analyses are performed in order to study the effect of some basic mining and economic parameters on the optimal pit design. The conclusions drawn can develop useful guidelines for decision making by the mine operator.

Jan 1, 1995