Search Documents

By Cengiz Karagüzel, Ömer Canıeren

The mobility of gold and silver metals from refractory ores is very low due to free metal ions in their bodies that bind the transportable and free metal molecules or they are encapsulated in minerals such as sulfides, arsenosulfides, carbonaceous, and clayey materials which make it difficult to extract them. As known from the literature, the enrichment of oxide refractory gold, silver ores, Ag, and Au-rich flotation concentrated from sulfur refractory ores can be leached in the chloride-hypochlorite solutions. In this work, the leaching approach was studied to extract silver ions from refractory ores in the presence of hypochlorite media under high pressure. The mineralogical and scanning electron microscopy analysis of the sample indicated that the silver was encapsulated in barite and quartz minerals in fine sizes. In order to obtain the optimum leaching conditions for the silver ore, the effects of several parameters, namely, temperature, leaching time, NaCl and NaOCl concentration, solid ratio, and particle size on the leaching recovery were investigated in detail. The leaching experiments showed that the highest silver recovery of 62.35% was obtained under the following conditions: temperature of 150 °C, oxygen pressure of 1800 kPa, leaching time of 2 h, concentrations of 2 mol/dm3 and 0.4 mol/dm3 for NaCl and NaOCl, respectively, the solid ratio of 30%, and particle size (d80) 15 μm. The results obtained from this study indicated that the enrichment of refractory silver ores to extract the silver encapsulated in barite and quartz minerals could be possible in the chlorite-hypochlorite under high pressure, a relatively shorter leaching time compared to conventional cyanide leaching.

Jan 28, 2021

By Viktor Lishchuk, Olof Martinsson, Tobias E. Bauer, Elena Haller

Freely accessible and non-confidential real-life geological data sets from mineral deposits are desirable for the wide range of applications in research and education. However, publicly available statistical data are limited in their number and quality—they contain reduced information about geological, geophysical, geotechnical, chemical, mineralogical, and other relevant properties of deposits. This makes such data insufficient for scientific purposes. However, the amount of geological knowledge obtained for a variety of deposits in the past allows the construction of an idealized synthetic ore body model using analytical approach. Such a model could be used for education purposes and testing basic scientific theories, e.g., visualization of deposit structure; teaching sampling strategies; testing new algorithms for mine planning; or comparing geostatistical modeling methods. This paper presents an analytical approach to simulate volcanic massive sulfide (VMS) deposits and shows how synthetic deposit model can be constructed and further used for studying sampling with drilling and simulating folding and faulting.

Jan 14, 2021

By Nate Ober, Heath Rushing

"Mining companies want to be in a position to move quickly and seize a favorable market or to keep their key staff productively busy. One of the problems for these companies is the time required to compensate for unavoidable impacts that the mine will have on the natural environment and to gain environmental permits. All too often, circumstances that were favorable when the project was proposed have become less favorable by the time all the hurdles have been cleared.Accordingly, many mining companies are interested in ways they can inject more predictability into their timelines for gaining environmental permits, shorten those timelines, and be more certain of getting the permits they need to carry out their next project.One increasingly popular way to do this is through a relatively new kind of service — the mitigation bank.Mitigation banks purchase property or easements through property that has been impacted by agricultural, industrial or resource activity. They then turn it around from an environmental point of view. This might include restoring streams and wetlands so that fish and aquatic organisms can survive, and animals have habitat and food to flourish.Appropriate native species of plants including trees and shrubs are planted, and steps may be taken to introduce wildlife to the new habitat. In some cases, a special focus is placed on creating habitat for rare and endangered species of plants or animals.The property is inspected by regulatory authorities, coordinated through an interagency review team (IRT). If the property is determined to be effective as natural habitat, the mitigation bank is then issued credits that it can then sell to development projects that are creating an unavoidable permitted environmental impact elsewhere. A mining company, for example, would buy credits to offset the aquatic impacts due to construction of a mine, access roads and other infrastructure — as required by the Section 404 Clean Water Act permit that governs those unavoidable aquatic impacts. The mitigation bank used for offset must have an IRT-approved service area that includes the location of the impacts."

Jan 11, 2017

By John B. Rigg

The title of my paper today is "public relations challenges for the pending minerals crunch". There isn't anyone in this room who would dispute. That the minerals industry has always had public relations challenges . . . No matter what the circumstances, mineral shortage or abundance. The industry suffers from an image that is second to none in longevity. It defies all actuarial formulas of the past or the future. Never mind that such an image is outdated, distorted, overstated, and reiterated. I submit that the minerals industry had public relations challenges long before there was anything called public relations. This account of egyptian mining practices, recorded for posterity by Diodorus Suculus at the end of the second century, b.c., is indicative. "On the confines of Egypt . . . And Ethiopia is a place which has many great mines of gold, where the gold is got together with much suffering and expense. The kings of Egypt collect together and consign to the gold-mines those who have been combined for crime, and who have been made captive in way . . . Sometimes only themselves, but sometimes likewise their kindred. "Those who have been consigned to the mines, being maw in number and bound with fetters, toil their tasks continuously both by day and all night long, getting no rest and jealously kept from all escape.

Jan 1, 1975

By J. K. Horbaczewski

The reclamation of an open dragline pit (Pond A3P-2) at the Gibbons Creek lignite mine in east-central Texas required neutralization of acid mine pit water. At the start of treatment with hydrated lime (Ca(OH)2) on March 28, 2000, the pond had partially filled with 913,000 m3 (740 acre ft) of pH 4.9 water. Another 666,600 m3 (540 acre ft) of pH 3.3 water was pumped in from an adjacent pit (PitA3P- 1). By the end of the project (July 5, 2000), a combined volume of 1,579,000m3(1,280ac-ft or 417milliongal) in PondA3P-2 had been successfully treated to pH 8.2 with 431 t (475 st) of lime. This was two to three times more neutralizer than laboratory trials and detailed chemical titration had predicted. The main reasons for the difference are thought to be the inadequate representation in a laboratory setting of some of the chemical reactions that occurred in the field, including incomplete mixing of reactants, reactions with clay minerals in the pit walls, the kinetics of biologically-mediated reactions and the kinetics of aluminum oxyhydroxide polymerization (aging).

Jan 1, 2002

By Yoichi Shimada, Katsuyuki Nishida, Shinichi Takahashi, Yasushi Okada, Yohei Nakamichi, Kazunori Oshiro, Taichi Terui, Sigehiko Sugie

"Temporary retaining walls are ordinarily used for tunnel construction work conducted using the opencut construction method. Retaining walls in such instances are typically installed vertically. However, shoring (such as struts and king posts) is required to ensure the stability of retaining walls in cases of excavation work to depths that exceed approximately 4 m. A new design and construction method that focuses on the effectiveness of retaining walls that are installed on an incline was studied with the aim of improving construction workability by omitting shoring. The inclined braceless excavation support (IBES) method, which was developed for use with the inclined buttress method, requires no shoring, even for deep-open-cut construction work and can be applied to deep excavation work on ground with a high groundwater level. This method has been applied at six work sites in Japan in recent years. This paper introduces the IBES design and construction method and presents verification results based on the design method, a model experiment, finite element analysis, and measurements obtained during construction work.INTRODUCTIONBackgroundIn the past, temporary retaining walls used in open-cut construction work have been installed vertically, and shoring (such as struts and king posts) has typically been used to ensure the stability of these retaining walls when the excavation depth reached 3–4 m. However, shoring interferes with structures built within excavations and requires box-outs and penetration sections in the structures, as well as concrete joints that raise concerns about their impact on the watertightness and long-term durability of structures (Figure 1).Shoring also narrows the space available for conducting construction work and reduces construction work efficiency, and the installation and removal of shoring increases the construction duration and cost. As a result, there has been a demand for ways to reduce or eliminate shoring to improve the quality of structures and construction work efficiency."

Jan 1, 2016

By Debasis Barman

TBM (TBM) mining in urban areas particularly under low overburden is a big challenge to design and excavate. During excavation of the Lucknow Metro project, in Uttar Pradesh, India the metro authorities encountered a design stretch where the TBM had to cross a sewer canal crossing of 15 m length under overburden of less than 1 m. Not only the stability of TBM due to uplift was of concern but also the stability of both banks. Most structures on the canal banks were non-engineered structures whose stability due to vibration of TBM was also of concern. Due to these risks, a method was proposed that met stability requirements for both ground and superstructures. The design was practical and cost effective to construct, and a collaborative exercise between the client, contractor and designer that took approximately 18 months to implement.

Jun 13, 2023

By CASSANDRA L. HOEBBEL, PATRICK L. YORIO, Emily J. Haas

This study revealed significantly less favorable perceptions of the existing organizational safety climate among workers in the underground coal-mining sector compared with those in the industrial-minerals and sand, stone and gravel (SSG) sectors. Consequently, it is important to consider pragmatic ways in which health and safety management systems (HSMS) in coal mines can alter processes to improve these perceptions. Given the interdependencies of safety climate factors and HSMS elements, researchers explored mineworker perceptions of the supportiveness of organizational safety climate factors among mineworkers and identified significant differences in perceptions across sectors. In this paper, we suggest that health and safety professionals in underground coal mining and organizations with fewer resources or less mature HSMSs focus on these factors to bolster support for proactive safety performance. Potential barriers to implementing or improving relevant HSMS elements and ideas to help foster more favorable perceptions of organizational safety climate are also discussed.

By N. Ripepi

"The Langmuir model has been widely used for the coal-methane sorption process via an isothermal test. However, even though the temperature-dependent Langmuir model were recognized theoretically and experimentally, the quantitative relationship between the Langmuir’s constants (a & b) and temperature have not been clarified and confirmed by lab test data. This paper collects 158 methane-coal sorption data under different temperatures, which apply the Langmuir model to consider the relationship between Langmuir’s constants (a & b) and temperature (see APPENDIX I). Even though the Langmuir model cannot be used to show the physical state of methane adsorption on coal, it is widely used because of its simplicity and the reasonable explanation of its parameters (a & b). The results from these published isothermal tests confirm that 1) there is no consistent relationship between Langmuir’s constant-a and temperature; 2) the Langmuir model is a temperature-dependent model, and the temperature-dependent feature is mainly shown by the relationship between Langmuir’s constant-b and temperature; 3) The relationship between Langmuir’s constant-b and temperature can be described by both the exponential and linear relationship with dried coal. This paper provides a database for temperature-dependent Langmuir’s model, which can be used for reservoir simulation of coalbed methane reservoir, coal seam degasification modeling for underground coal mines considering the heating effect induced by geotherm and heat injection (via hot water, hot steam, ultrasonic, etc.). INTRODUCTION The isothermal test for gas sorption on coal is one of the fundamental tests in Coalbed Methane (CBM) recovery fields, such as underground coal mine methane degasification, CBM gas-in-place estimation, and carbon dioxide sequestration in un-minable coal seams. Generally, two methods, volumetric and gravimetric, are employed to obtain isothermal data (Bush, A. & Gensterblum, Y., 2012). Based on these two approaches, a series of commercial and self-assembled instruments are built and several calculation methods are used to obtain isothermal data (Bush, A. & Gensterblum, Y., 2012, Gasparik, K., 2014; Goodman, A. L., et al, 2004; Zhang, L., et al, 2013). In the post-processing stage, many models are provided to analyze isothermal data in order to understand the storage mechanism of gas in coal. Common models include the Langmuir model (and its extended forms), the pore-filling model, multilayer adsorption model (BET), and the Gibbs’ model. Among these models, the Langmuir model is the most widely used for its simplicity and functionality. The Langmuir model is expressed as follows:"

Jan 1, 2016

By W. J. Douglas

The mine manager in today's environment is faced with a wide variety of problems and challenges which must be addressed if efficient and profitable operations are to be achieved. Expansion of operations has, in many instances, resulted in inexperienced work crews, face supervisors, and superintendents. The complexities of a mining system preclude rapid movement through the learning curve for moat personnel. The management of production suffers both from this inexperience and the lack of standard procedures and methods for planning, schedul ing and analyzing production systems. The lack of visibility of information, as well as of the operations themselves, due to their remoteness, adds to the problem of production management.

Jan 1, 1980

By Christopher Newman, Robert Dupuy, David Newman

"The development of a multiple level underground mine is a complex task in which geology, engineering, ground control, and unit operations are integrated into a single mine design. The components are inter-dependent and must function cohesively to ensure a profitable underground mining operation. To optimize reserve recovery, mine planning should begin from the lowest level and progress up. This limits any misjudgments or oversights of a given level affecting the underlying levels and ensures the ability to maximize recovery from each level.Mine planning should start with the exploration and characterization of the geologic setting. Once the reserve geology and quality is well understood, then mine planning can begin with respect to the following:,Orientation of mine works with respect to horizontal stress,,Access to the reserve,,Determination of opening widths,,Selection of back, floor horizons and pillar centers,,Selection of development and secondary mining heights,,Appropriate interburden thicknesses, and,Examine the stability of the multiple level mine through numer¬ical modeling.The multiple level mine design process and decisions are presented through a case history example. The theme is that there is one opportunity to “get it right” as well as many chances to overlook a small aspect within the design that will plague the mine throughout all levels and through the entirety of its operating life.INTRODUCTIONAs surface quarries reach their economic stripping limit and encroach on mineral and/or reserve boundaries, they approach the end of surface mineable reserves. Furthermore, modern urban sprawl has placed previously remote surface quarries within suburban development and neighborhoods, leading to significant increases in noise, dust, and vibration grievances by the community and regulators (Newman, 2017). Many mining operations have begun year-round production of underground reserves to meet growing market demands. This does not permit the typical sequence of stripping overburden in the winter to provide limestone to mine during the construction season. Underground stone mining operations in the United States commonly utilize a room-and-pillar mine layout with drill-and-blast production methodology for the development of the reserve. Within the Midwest and Eastern regions, thick and flat-lying limestone formations lend themselves to the utilization of multiple level mining layouts. While a multiple level mine plan will increase the overall recovery of the reserve, greater overburden depths, multiple level geometry, and the presence of discontinuities all require an emphasis on ground control for the planning and development of a safe and productive multiple level underground stone operation."

Jan 1, 2019

By H. F. Haller

Large volume sand plugs are placed in tunnels to stem underground explosions at the Atomic Energy Commision's Nevada Test Site. Placement through long, narrow accessways is like stemming coyote holes and blast chambers in mining and construction. Experience with several other methods showed that pipeline conveying could be preferable. Small scale tests justified predicting a placement rate of 20 y. p. h. at 1000 feet, with a modified gunite placer. The initial production trial placed over 2000 c. y. and was estimated to effect a small cost saving after paying for new equipment. Initial problems included duct replacement and supply delays, dust, and other personnel hazards. Operations analysis and SOP'S reduced delays during the second field trial, minimized hazards, doubled production. Re cent re search and operations analyses produced data on abrasion resistant ducts, identified minor equipment modifications which can improve production, developed techniques for impact compaction to 90% ?maximum? and for extension of the practical range to 2000 feet. Twenty-two illustrations include an air consumption-distance chart.

Jan 1, 1967

By Cesar Carrasco, Heath Arvidson, Mark Forster

Block models built to represent the geology and rock characteristics of mineral deposits represent huge complex data sets, which form the basis of strategic and business planning, and public reporting of Mineral Resources and Mineral Reserves. Recent advances in cloud computing and database technology developed for the Internet of Things offer a different way of working with these critical data sets. Enabling a cloud based, open data structure with high performance data analytics capability presents a compelling improvement in governance and a democratization of ore body knowledge that can lead to automation use cases that support the digitalization of mining.

Jun 25, 2023

By J. L. Brinkman

"One of the most common emissions from detonating explosives are nitrogen oxides (NOx), which are potentially deadly if inhaled. Lab studies estimate emission quantities, though great variation is shown based on site-specific conditions, and lab tests may not fully represent field results. Field VALUES (have not been measured due to the vast area affected. OSMRE recently promised to release a ruling regarding surface mine NOx production. Once the ruling is implemented, it may eventually be necessary to monitor site-specific NOx production from blasting. A small unmanned aerial vehicle system (sUAS) is able to carry a NOx gas monitor, rapidly travel to the blast location, and to follow resulting clouds of dust and emission gasses. This project will perform laboratory tests to expand on current estimations, determine an optimal method for collecting data, and evaluate the ability for this unique application of sUAS to assist in health risk assessment for mine employees and nearby communities. Additionally, large initial NOx concentrations do not necessarily correlate to unsafe conditions, and this project will be ground breaking in observance of surface blasting emission dispersion. The project is still in early phases at the time of submission for this paper (Nov 1, 2017). Therefore, this paper focuses primarily on summarizing background research related to the project and a description of the project plan. INTRODUCTION Nitrogen oxide gases (NOx) are common emission by products of surface mine blasting. These gases can potentially cause risk to human health and safety, both for mine workers and communities near the blast site. However, these emission quantities are largely unmeasured and no attempts have been made to relate these VALUES (to human health risk. The primary objectives of this project are to determine actual quantities of emission gases produced during surface blasting, to evaluate immediate and long-term risks to nearby people, communities, and ecosystems, to develop a system for mine employees to easily monitor emission and risk levels, and then provide guidelines for mitigating health risks based on a location’s emission results. BACKGROUND Current research regarding health risk produced by surface mine blasting NOx emissions is extremely lacking. Estimations have been made based on laboratory research, though these same test results show wide ranges of possible gas quantities produced based on site-specific conditions. Even if these estimations are accurate, no method has been created to relate gas quantity produced to human exposure concentrations. To further understand this field, background research was studied pertaining to blasting emission gas formation, laboratory and field measurements, harmful effects of blasting emission gases, and relevant government regulations. Background on Blasting Emission Gases"

Jan 1, 2018

By Meng Li, Hao Nie, Weitian Ding, Mamdouh Omran, Ying Li, Yao Ge, Yaowei Yu, Abourehab Hammam, Lei Zan

This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H2 atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H2 is more efficient thanwith CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H2 gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H2 atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H2 atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion.

Sep 29, 2020

By V. O. Tenorio, J. Puell

"Dump design is critical to effective mine planning in large scale open pit mines. Capital and haulage costs are considerable from early stages and through the life-of-mine as these dumps gradually become immense structures. Delivered mining rates, as well as certain spatial and physical constraints, provide a set of parameters of mathematical and economic relationship that creates opportunities for modeling and thus facilitates the measuring and optimization of ultimate dump design by using programming and empirical techniques while achieving economic objectives. This paper presents a methodology to optimize the ultimate dump design by minimizing its total dumping costs. The methodology consists of the formulation of a generalized model based on the relationship of the main dump parameters, followed by the use of linear programming to find the solution that minimizes the haulage total cost, and finally through a series of iterations, modifies the preliminary solution by projecting it to the topography and creating the ultimate dump design. A case study applied to a waste dump exemplifies this methodology. INTRODUCTION Open pit mine operations move large amounts of material on a daily basis from the shovel faces to the appropriate destination points. Hustrulid et al. identified three major destination places where the material receives downstream treatment after its delivery: mill processing, leaching dumps, and waste rock dumps [1]. The corresponding destination is given by a cut-off grade criteria, ore type, and the possibility of obtaining the maximum metal recovery. Dump leaching technologies have developed substantially since 1975 [2], and have enabled mining facilities to beneficiate low grade sulfide and oxide ores. As a consequence, the number of active dumps have increased since then and the entire mine configuration, which is limited in itself, has changed. The proper location, design, and construction of a mine dump must serve the safety, environmental and economic goals of the long-range mine plans. Therefore, an optimized use of the available surface area in the mine is highly desired."

Jan 1, 2018

By Robert B. Tippin

A number of recent studies 1-4 suggest that steelmaking expansion might be achieved more economically by a combination of the prereduction furnace and the electric steelmaking furnace rather than through new blast furnace construction. Supergrade concentrates would be the first step in an evolving technology which bypasses the blast furnace and in which the concentrates are first made into pre¬reduced pellets and then used directly in electric steelmaking, Prereduced pellets made from superconcentrates should not only be competitive with scrap, but should be a preferred feed for the electric furnace because of the absence of such residual elements as copper and nickel. Furthermore, geographic areas remote from present steelmaking centers may find the electric furnace to be an economical method of providing local steel requirements. The development of successful methods of producing superconcentrates may also be expected to find application to conventional blast furnace burdens. The need for methods of increasing grade of domestic concentrates will become increasingly urgent in the face of competition from high grade imports. Only a small percentage of domestic iron ore production can qualify as superconcentrates, (Superconcentrates for the purpose of this investigation are limi¬ted to those concentrates which contain a maximum of 2 percent S'02). During the last several years the Twin Cities Metallurgy Research Center of the Bureau of Mines has directed research efforts to develop methods of manufacturing superconcentrates from present standard grade products by cationic flotation, screening, and magnetic separation.

Jan 1, 1971

By K. A. Lewandowski

Heap leaching efficiency is reduced by poor solution flow characteristics (channeling and ponding), which result from compaction and fines migration. Agglomeration of the ore can prevent compaction and immobilize fines, but copper leaching requires an acid-resistant binder to stabilize the agglomerates. Until now, there has not been a satisfactory way to evaluate whether a binder was effective, other than squeezing a handful to see if it ?feels right.? Procedures have been developed to quantitatively determine whether a binder produces agglomerates that can withstand compaction in an acidic solution, and have identified several binders that will provide sufficiently compaction-resistant agglomerates for copper heap leaching. Keywords: Copper heap leaching, Binder performance, Compaction

Jan 1, 2010

By John N. Murphy

The environmental status of underground mining operations is critical to the health and safety of the miners; particularly in a large mine, the multitude of interacting parameters that can favorably or adversely affect the environ-mental status makes the manpower requirement of the routine checking of specific areas and conditions a formidable one. While the concept of environmental monitoring for miners has been considered for some time, until recently the availability of sensors to reliably measure the parameters of interest severely limited the utility of such systems. The status of sensors for mine use and the evaluation of environmental monitoring systems is reviewed.

Jan 1, 1977

By Christopher Mark

Successful longwall gate entry design requires control of both vertical and horizontal stresses. Vertical, or overburden, stresses are most severe in the tailgate where they are concentrated by longwall panel extraction. Horizontal stresses, which are generally tectonic in origin, can be highly destructive during the development and headgate phases of longwall mining. The goal of this paper is to present the current state-of-the-art in detecting and controlling horizontal stresses. The information presented was collected through site investigations at 45 U.S. longwalls and an international literature review. The paper begins with a discussion of the present knowledge of regional in situ stress fields in the U.S. A review of available underground stress measurements from coal mines is presented, along with data collected by structural and petroleum geologists. The combined evidence indicates that a persistent ENE-EW trending stressfield is present throughout the eastern coalfields. Experience with horizontal stress in longwall mines is addressed next. The paper focuses on the northern Appalachian region, where the effects of horizontal stress have been most evident. Three case histories are discussed in detail, and the solutions each developed are highlighted. Observations made in the Southern Appalachian, Alabama, and Illinois coalfields are also described.

Jan 1, 1991