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By D. M. Abbott

The problem with best practices occurs when they do not work. This happens when the seldom-stated assumptions underlying the practice are not met. This paper provides some examples for the mining industry: (1) when core splitting is inappropriate, (2) when the use of fire assays for placer samples is inappropriate, and (3) when high-grading may be acceptable. Geologic conclusions are, in the final analysis, expressions of judgment predicated upon knowledge and experience. A geologic conclusion, however, purports to be more than an arbitrary determination—it is reached as a consequence of method. No specific method is required, but the method used must be an orthodox method, in accordance with orthodox definition of terms, and the one best adapted to the dealing with the questions asked about the property in question. Whether the so-called “best practice” is really applicable to the job at hand must be decided on the basis of professional scientific judgment. When one decides to deviate from a published “best practice” for sound scientific reasons, describe in detail in the report what the so-called “best practice” is, why it was inappropriate for the project, and why the method used was better. If one becomes aware that a “best practice” is being proposed, actively urge those proposing it to include in its description the underlying assumptions that must be met in order for the “best practice” to be valid.

Jan 1, 2014

By F. L. Wilke

Truck haulage costs form a major part of the total mining costs in hard rock open pit, mining operations. In order to minimize these costs one has to - determine the optimal truck fleet (type, size and number of trucks), and. simultaneously - determine the optimal organization of running the haulage system, i.e. especially select the optimal dispatching strategy in order to ensure maximal utilization of the trucks, and simultaneously - establish a reliable maintenance and servicing system to guarantee maximal availability.

Jan 1, 1982

By N-h. Mao

We applied kriging (geostatistics) to interpret the structure of basement rock in Yucca Flat, NTS from borehole data. The estimation error for 118 data is 81 m comparable with those based on both gravity and borehole data. Using digitized topographic data, we tested the kriging results and found that the model validation process (Thomas option) on data gave a fair representation of the overall uncertainty of the kriged values.

Jan 1, 1985

By Lauro Lacerda

Shotcrete is a highly adaptable and widely used underground construction material at infrastructure and mining projects around the world. In fact, many projects could not have been completed without its utilization. As underground projects became larger the use of mechanized wet-mix spraying gradually replaced manual dry-mix shotcrete applications. This paper details some of the reasons for that and provides information on the equipment and operational factors including safety and productivity required to successfully complete underground shotcrete projects.

Jun 13, 2021

By William Bergeson

"BACKGROUND As of December 2015, there are roughly 475 road tunnels within the United States according to the most recent national tunnel inventory data compiled by the Federal Highway Administration (FHWA); whereas, there are more than 615,000 highway bridges on public roads. The FHWA estimates that tunnels represent nearly 100 miles of Interstates, State routes, and local routes. Tunnels are part of the national transportation infrastructure and represent a significant financial investment for the owner and, hence, the tax payers. Tunnels, that are not properly maintained, usually require more extensive repairs and consume more resources. Tunnels must provide safe, reliable, and effective transportation even as these structures age and deteriorate. Furthermore, tunnels generally remain in service for extended periods of time due to their very high construction costs. For example, many tunnels were constructed decades ago during two historic periods of highway system expansion; the first period correlated with the era of public works programs linked to the Great Depression of the 1930-40s; and the second period of expansion occurred with the building of the interstate highway system in the 1950-60s. As such, these tunnels are fast approaching 60 to 80 years old. Congress enacted the Moving Ahead for Progress in the 21st Century Act (MAP-21), which was signed by the President on July 6, 2012. This legislation followed a fatal tunnel incident on July 10, 2006 and a National Transportation Safety Board (NTSB) report1 that noted the importance of conducting regular tunnel inspections. MAP-21 authorized the Federal Highway Administration (FHWA) to develop a mandatory inspection program for all tunnels on all public roadways (Bergeson and Ernst 2015): To help safeguard tunnel users and to ensure reliable levels of service, the FHWA developed the National Tunnel Inspection Program (NTIP), which is comprised of the National Tunnel Inspection Standards (NTIS), the Tunnel Operations Maintenance Inspection and Evaluation (TOMIE) Manual, the Specifications for National Tunnel Inventory (SNTI), and the Manual for Bridge Evaluation (MBE). The data collected from the program will be stored in a National Tunnel Inventory (NTI) database. A comprehensive and refresher training program was also developed to help qualify and certify key tunnel inspection personnel to include the program manager and team leader."

Jan 1, 2016

By L. H. E. Weyher

In a previous paper presented at the 1966 Annual Meeting of AIME we reported our work, conducted at the Pennsylvania State University, on the hydrocyclone washing of fine coal.' The initial evaluation based on that work demonstrated the feasibility of hydrocyclones as fine-coal cleaning devices, and in that previous paper we presented selected test data that showed in principle how product yield and assay respond to variations of the major cyclone operating variables. The present paper reports in greater detail on the findings and presents a comprehensive evaluation of our data as follows: ? Hydrocyclone throughput rates were related to feed pressure and other variables by regression equations. These equations are compared with other capacity- versus-pressure drop expressions taken from the literature on classification cyclones.

Jan 1, 1968

By Yerkezhan Madenova, Kairat Kalmurzayev

This study intends to demonstrate the engineering application of ground penetrating radar (GPR) that would enable site engineers to prevent the high cost of blind drilling. At the tailing dump located in Zhairem Mining and Processing Plant, the challenge of sheet pile driving is encountered due to the indefinite watertight clay layer deposition depth that serves as a protective layer against groundwater contamination. A numerical model of the soil underlying the tailing dump is built using the existing hole data to compare and confirm the existing geological cross sections for three profile lines along the south and southeast parts of the tailing dump. GPR is employed to investigate the subsoil geological structure and detect the watertight clay layer deposition. On the basis of radargrams tied to the existing borehole data in the numerical model, 21 drill hole locations are suggested to assess and confirm the clay layer depth along profile lines at the tailing dump. The drilling results of the suggested holes confirmed the expected depth of the clay layer. It is concluded that GPR is a practical and economic subsurface mapping method that can prevent the high cost of blind digging of the ground and orient the drilling operations effectively.

Jan 12, 2023

By John W. Straton

Following the completion of the paper presented in February, 1972, data were received from many other mines and some original respondents submitted more complete questionnaires. The computer program was changed to permit the results to reflect more clearly all the data reported by the mines. The original paper was revised to reflect the new information. There were significant changes in some numerical values, particularly where the size of the sample changed appreciably. Some limited samples considered originally in arriving at conclusions were not relied on in this revision. The revised tables and text are of the same design and format as the original paper.

Jan 1, 1972

By Douglas J. Uhren, Gary W. Gilbert

This paper describes the risk elements associated with difficult glacial geology, including boulders, heavy groundwater inflow, and potential running soils all coupled with a potentially corrosive service environment. The matrix workshop for the 168-inchfinished diameter sanitary sewer interceptor tunnel in Columbus, Ohio is assembled with the Design Team and the Owner’s design, operations, and fiscal staff. Corrosion protection alternatives are compared against cost and non-cost parameters with relative risk and weighting factors assigned. The Owner working in cooperation with the Design Team uses the matrix workshop to se

Jan 1, 2001

By L. Yuan, J. H. Rowland, R. A. Thomas

Hydrogen (H2 ) gas released during battery charging can result in cross-interference for carbon monoxide (CO) sensors used for early fire detection and compromise the integrity of the mine atmospheric monitoring system. In this study, a series of laboratory-scale and full-scale experiments were conducted to evaluate the responses of different CO sensors to H2 gas. In the laboratory-scale experiments, H2 concentrations in the airflow are constant, while in the full-scale experiments, increasing H2 concentrations generated as a byproduct of charging the batteries at the battery charging station rise to the sensors under different ventilation scenarios. The H2 concentrations at the CO sensor location were measured using H2 sensors and were correlated with the CO sensor response. The effects of ventilation and sensor location on the CO sensors responses were also analyzed. The results of this study can help mining companies to select appropriate CO sensors and improve the deployment of these sensors to safeguard underground miners.

By Paul M. Godlewski, Roberto J. Guardia

Hundreds of highway and rail transportation tunnels in North America have been rehabilitated in the last two decades. Tunnel rehabilitation is usually dictated by an owner’s need to extend the working life of the structure, but typically has the added benefit of increasing capacity (greater speed or increased clearance) and enhancing safety. Not only has rehabilitation proven to be an economical alternative to new tunneling, but it can be safely accomplished by working during short work “windows” without taking the tunnel out of service. This paper presents methodology for planning and designing of tunnel rehabilitation projects, and case histories illustrate successful excavation and support technologies.

Jan 1, 2003

By P. F. Ziemkiewicz

This project evaluated the performance of nine passive treatment methods by studying 137 treatment units in eight eastern states. Performance was normalized according to construction cost, projected service life and tons of acid load treated. Results were dimensioned as $/tons of acid load treated/year. These costs were then compared to those of chemical treatment. Sites that achieved acid load reductions at costs below those of chemical treatment were considered successful. In addition to evaluating the performance of the treatment methods, this paper describes the various passive treatment systems, their applications and performance data for individual treatment units.

Jan 1, 2003

By Mark Leggett, Kevin Roberts

The need to modernise and increase the safety provision of older road tunnels raises challenges in maintaining the operation of the tunnel during such improvement works. The Mersey Kingsway twin road tunnels located in Liverpool UK, constructed in the late 1960s, have had three new cross passages constructed to allow emergency evacuation from one tunnel to the other tunnel and provide safer access for emergency services. The 3200m long road tunnels are lined with an unusual reinforced concrete steel-faced segmental lining with a paint finish. Construction of the cross passages occurred during night possessions with the tunnels returned to normal operation during the daytime. Constructed through water bearing sandstone and lined with precast concrete segments, the passages required advance ground treatment and support works. This paper presents the historical background to the Mersey Tunnels and describes the procurement strategy, design and construction approach adopted for these important safety improvements.

Jan 1, 2003

By R. Venugopal, V. K. Saxena, Veerendra Singh

"Ore morphology plays a vital role during the milling and liberation of minerals. This study was carried out to understand the role of mineral crystallography and mineral interfaces on the milling and liberation processes. Data related to mineral crystallography, Vickers Hardness Number and beneficiation processes were collected from literature, and detailed statistical analysis was conducted to relate these parameters. Review of the crystallographic information of minerals present in ores indicates that molecular weight and cell parameters significantly affect milling and liberation characteristics. Mineral interfaces were classified into the three categories of coherent crystals, semi-coherent and incoherent crystals, and breakage behaviors were studied. The studied cases revealed that these material interfaces control the micropore properties that play a vital role in the initiation of intergranular and intercrystalline fractures which occur in siliceous manganese ores and dolomite as a result of thermal treatment. In contrast, banded hematite jasper and coal exhibited a much more complex fracture pattern due to their coherent interfaces and finer physical associations. This study explains the effect of the various types of interfaces on milling, and the approach can be helpful in developing a methodology to enhance mineral liberation with minimum energy consumption.IntroductionComminution is a vital unit operation in the mineralprocessing, cement-making, power-generation and pharmaceutical industries. Its importance in mineral beneficiation operations is increasing every year as a result of the growing need to exploit lower-grade ore bodies and process reject materials (Blazy et al., 1994; DOE, 2005). Low-grade ores require significant energy during grinding to liberate the valuable minerals, which are further separated from the gangues by various beneficiation methods. Various attempts have been made to enhance mineral liberation during grinding to minimize energy consumption. Most of these studies focused on the analyses of the compression mechanism, chemical additives, thermal treatment, microwave treatment and electric disintegration (Klimpel and Austin, 1982; Norgate and Weller, 1994; Bearman et al., 1997; Kumar et al., 2010; Wang et al., 2011; Singh et al., 2012). However, many of these efforts had limited success, and there is a need to see the problem from a fresh perspective."

Jan 1, 2015

By Hassan El-Shall, El-Sayed A. Abdel Aal

The major goal of this study is to decrease iron content in wet-process phosphoric acid. Reducing the amount of post-precipitated sludge in the acid is another important objective in this investigation. In order to achieve these goals, research efforts have focused on bench scale testing of an iron-chelating reagent to remove iron from phosphoric acid produced from South Florida high-iron and -magnesium phosphate concentrate, and plant testing using freshly produced concentrated acids for reducing the post- precipitated sludge. The data obtained in the above studies suggest that the addition point of the precipitating reagent is very important, as the precipitated iron compound has higher solubility at higher P2O5 concentrations. Up to 60% Fe2O3 removal efficiency is achieved depending on the amount of the reagent, concentration of acid used, and operating conditions. The addition of precipitating reagents to freshly concentrated phosphoric acid leads to a decrease of up to 84% in sludge volume percentage depending on acid type and clarification conditions. Decreasing the volume percentage of the sludge facilitates acid handling as well as decreases the adherent water- soluble P205 leading to lower total P2O losses.

Jan 1, 2002

By Jacob Grasmick, Bill Newns

Despite ongoing digitization and “hardware” technological advances, geotechnical uncertainty remains the most significant risk in underground and tunnel construction. And, whilst they are commonly held up as an example of the sophistication of the industry, the practice of drafting and using geotechnical baseline reports is subject to a wide range of influences, not all of which support good risk management. Uncertainties in predicting ground behavior, the gap between the pre-construction assumptions, and the systemic response to construction remains a significant technical and communication challenge. Accordingly, this paper presents a framework to quantify geotechnical uncertainty using geostatistics and translate these into practical tools for ground risk management throughout planning, procurement and construction. Adopting even some of the principles of this framework should provide improvements to contract risk management and should assist to minimize the potential for commercial losses.

Dec 1, 2022

By L. Adler

A fairly complex analysis is required to select, or evaluate a piece of excavating and bulk handling equipment and obtain its performance. At present there is little agreement as to what specific points should be considered, and even less on what procedure to follow. This paper provides both of these in a consistent and direct form. The analysis applies to all types and sizes of equipment from the bulldozer and the continuous miner, to the B.W.E. The importance of the equipment characteristics, job activities, and work conditions are stressed and separate analytical stems are established in a flow chart for these. They are combined using suitability tests in the following steps: 1) problem statement, 2) natural conditions, 3) suitability guidelines, 4) appropriate equipment types, 5) operational activities, 6) encumbered space, 7) geometric design, 8) equipment sizing, 9) failure and limits, 10) performance and consumption, 11) public policy checks, and 12) costs and profitability. Public policy and economics while considered throughout receive emphasis towards the end. The procedure is iterative, containing distinct feedback loops. Specifying the steps and sequence provides a necessary structure which has long been overdue.

Jan 1, 1983

By L. Gutierrez, J. S. Castro S. Laskowski

Water is a medium in which flotation takes place, and flotation efficiency is highly dependent on water quality. Of the total water resources on Earth, less than 2.5 percent is fresh water. This water is used in agriculture, by households and by industry. Among the industrial users of fresh water, the mining industry occupies an important position. Furthermore, mining operations are often located in arid areas with very limited access to fresh water. The demand for and shortage of water in these parts of the world, such as the Atacama Desert in Chile, makes the use of seawater by the mining industry the only sustainable solution. 

The response of 174 domestic water supplies to longwall mining of the Pittsburgh coal seam was compared to various physical parameters. Sixty-four percent of domestic water supplies returned to service without the need for intervention, while thirty six percent required intervention to reestablish a suitable water supply. Domestic well response is strongly correlated with the topographic setting. Valley wells showed the least effect while hilltop wells showed the greatest effect. Well response was also found to be correlated to the location of the well above the mining with greater effects observed in zones of surface tension and compression, and fewer effects in zones which are stress neutral. Ground water supplies remained unaffected or were re¬established at 149 of 150 sites, indicating that ground water resources remain available to domestic wells after mining. Results of this study support the stress-relief model of ground water flow in the Northern Appalachian Basin. Longwall mining's effect on this system is to locally increase fracture connectivity in the near surface zone. This may shift the zones of saturated fractures to greater depths beneath hilltops and hillsides, and increase recharge and storage in valleys. General trends in well response are predict¬able utilizing the stress relief conceptual model, the topographic setting of the water sources, and their location over the mine.

Jan 1, 1986

By Aldo F. Barsotti

The production and consumption of industrial minerals in the United States traditionally have played important roles in mining and in the supply of the bulk of basic raw materials to the economy. This diverse group of minerals extracted and consumed by a variety of industries accounts, on a weight and volume basis, for most mineral-based products consumed in our economy. Industrial minerals form the bulk of the basic raw-materials feedstock for most of the construction, agricultural, and inorganic-chemical-manufacturing sectors, and a good portion of the transportation, manufacturing, organic chemical, and service sectors of the U.S. economy. In this presentation, I discuss current estimates of the amount and value of industrial minerals mined compared with all mining in 1997. I then present a summary of 1997 production of industrial minerals by several end-use industries. This is followed by a historical perspective of the consumption of industrial minerals as a subset of all basic materials, with special emphasis on the aggregates industry. The presentation concludes with a look at the geographic distribution of industrial mineral operations in the United States and some thoughts about the future.

Jan 1, 1999