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By Jan E. Nesset, James A. Finch, Wei Zhang

"Bubbles are unquestionably the heart of the flotation process. Their size and combined surface area are largely what drive the recovery process. This suggests that plant engineers should be aware of where their plants are operating with respect to what is achievable for these key parameters. The paper presents a model of how the key operating variables of frother type and concentration, gas rate, altitude (above sea level) and viscosity affect the Sauter mean bubble size (D32) and bubble surface area flux (Sb). The results are compared to a set of plant measurements that demonstrate the benchmarking capability of the approach. A case study is used to link hydrodynamic change to improved metallurgical performance.INTRODUCTION At the beginning of the 20th Century the early practitioners of flotation were aware of the importance of understanding bubble behaviour (Rickard, 1916) but measurement of individual bubble and gas behaviour in the industrial environment was not possible due to a lack of adequate sensors. This situation was not rectified until three quarters of a century later with the advent of industrially-robust sensors developed, notably, at the University of Queensland’s Julius Kruttschnitt Mineral Research Centre (JKMRC) (Schwarz & Alexander, 2006) and McGill University (Gomez & Finch, 2002). What emerged was not the chaotic environment perhaps expected, but defined relationships between gas rate, gas holdup, bubble size and the total surface area of bubbles. These relationships could be defined by mathematical expressions and predicted from an understanding of the key process variables (Gorain, Franzidis & Manlapig, 1997; 1999) (Hernandez-Aguilar, Gomez & Finch, 2002) (Gomez, Cortes-Lopez & Finch, 2003) (Nesset, Gomez & Finch, 2007). The early JKMRC work focused on a large pilot cell (3 m3) installed in plant environments, while the McGill work was initiated on flotation columns (Finch & Dobby, 1990) (Xu, Finch & Uribe-Sales, 1991) and later adapted to industrial mechanical cells (Cooper, Scott, Dahlke, Finch & Gomez, 2004) (Dahlke, Gomez & Finch, 2005) (Nesset, Gomez, Finch, Hernandez-Aguilar & Difeo, 2005). Yianatos of Santa Maria University (Chile), a graduate of the McGill research team, carried the work to industrial settings in South and Central America (Yianatos, Bergh, Condori & Aguilera, 2001). The methods of gas dispersion measurement are now well accepted and most major research centres and flotation cell manufacturers have adopted the technology (Pyecha, Sim, Lacouture, Hope & Stradling, 2006) (Yañez et al., 2009) (Collins, Schwarz & Alexander, 2009)."

Jan 1, 2012

By Georgene Renner

At the beginning of the 1990s, Communism fell and signaled the end of the Cold War. The world rejoiced but also watched and waited to see how those countries would restructure themselves. The 1990 SME Annual Meeting was held at the Salt Palace Center in Salt Lake City, UT. The keynote session featured Alistair Frame, chairman of RTZ; Paul Queneau, professor of metallurgy at the University of Utah; and TS Ary, director of the U.S. Bureau of Mines. The SME Board of Directors voted to hire a Manager of Public Information and Education to be the GEM Program coordinator. This person was to collect and disseminate information that could be used by individual members and Local Sections to interface with government personnel and the general public.

Jan 1, 2007

By L. Kaufman

A range of processing conditions and compositions have been evaluated in order to optimize the properties of TiB2-(Ni,Cu) composites for application as a non-sparking tool material for use in coal mining operations. Fifty billets containing from 70 to 9S weight percent titanium diboride were hot pressed at 3000 psi between 2400°F and 2650°F. Samples which were cut from these billets were used to measure hardness, bend strength and impact strength so that composition/processing optimization could be effected. Eight compositions selected on this basis were evaluated by incendivity tests in order to choose the best composition. The best results were obtained for an 85 w/o TiB2-12 w/o Cu-3 w/o Ni composite hot pressed at 2650°F and 3000 psi. This material appears to be the best choice for fabrication of coal cutter bits to be evaluated in field tests.

Jan 1, 1973

By Scott Rosenthal, Kyle Murphy

This paper discusses the trials and tribulations of obtaining Velocity of Detonation (VOD) readings in small diameter blast holes in an underground mine. Montana Technological University (Montana Tech) obtained a time-domain reflectometer (TDR) type VOD monitoring unit. Purchase of the VOD monitor was justified on verifying explosives performance used in Montana Tech’s practical underground mining class and provide a teaching aid for the school’s rock fragmentation class. Before demonstrating the unit to students, we figured we better learn how to use it first so we give the students an appropriate experience. Our first learning was in obtaining the correct coaxial cable for the VOD monitor and how to properly terminate the cable. Once the cable was on-site and terminated, VOD testing could commence. Use of the VOD monitor was tested underground in small diameter holes (1.5-inch, 38 millimeter) pneumatically loaded with ANFO. After a few failed trials, and follow-up discussions with the supplier, VOD readings were obtained for the ANFO loaded holes. Additional readings were obtained for a pre-split product and detonating cord to satisfy our curiosity that the unit was performing as specified by the manufacturer. This paper will share our learnings in the hopes that others can benefit.

By P. R. Perry

This publication is a compilation of tested methods for the analyses of titanium tetrachloride, titanium sponge, and various intermediate materials and products. They are presented in concise form without the detail usually found in publication of new methods because many of them are modifications of well known procedures. The Electrometallurgical Experiment Station, Boulder City, Nev., has been developing titanium production methods since 1945. Most of this development was on a modified Kroll Process but also included work on sodium reduction and electrolytic methods. During these years a large variety of samples were analyzed. Most of the analytical problems were solved using published methods or modifications of the same. At the start, there were no published procedures for analyzing titanium sponge using spectrochemical methods. A great deal of study was given to testing several of the well known techniques, and some of them, such as direct sparking of the metal, proved to be completely unsatisfactory. Solution-spark techniques were finally tried, and satisfactory procedures were developed for some of the more common impurities. These spectrochemical methods were then put into routine use for several months before their publication.2/ Some new modifications have been made, and techniques have been developed to determine other impurities found in titanium sponge and tetrachloride. All spectrochemical methods used in 1954 are included in this publication.

Jan 1, 1955

By L. B. Berger

Tests and observations of a Diesel-powered locomotive used for under-ground haulage, in a-clay mine were made by representatives-of the Bureau of Mines .primarily to determine the composition of the exhaust gases produced by the engine under actual haulage conditions-and to determine the effects of the operation on the quality of the mine atmosphere. In addition to ascertaining these conditional t proved interesting to analyze the test, data in regard to certain other performance, characteristics of the engine. This report presents results of tests of the mine locomotive, prefaced by a brief resume of the performance characteristics of Diesel engines to facilitate discussion.

Jan 1, 1948

By M. Fan

Froth flotation is the most widely-used method of separating fine coal, especially coal with coking properties. However, froth flotation is not efficient for treating ultrafine coal and coarse coal particles. Our previous fundamental test results demonstrated that cavitation-generated nanobubbles can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubble on the flotation performances of different particle size fractions of coal was investigated using a bank of 10-liter flotation cells, a specially designed 50 mm inside diameter column and a 152 mm inside diameter column. It was found that nanobubbles that were either directly formed on or subsequently attached to the surface of coal particles during coal froth flotation process improved flotation efficiency. The use of nanobubble in a bank of mechanical cells flotation and column flotation significantly increased the flotation recovery at a given product grade. Nanobubbles increased the flotation rate constants of different coal particle sizes. The presence of nanobubbles in flotation slurry could extend the lower and the upper particle size limits for effective coal flotation.

Jan 1, 2012

By Robin B. Dill, Mark Pelletier, Daniel J. Dobbels, Subodh Bhaumik, Daniel J. VanRoosendaal

Although primarily cut-and-cover excavations are required for replacement of the existing elevated I-93 interstate highway through the heart of Boston for the Central Artery/Tunnel (CA/T) project, some mined tunnel construction was also undertaken. The mined tunneling conducted was the 22-m-wide northbound roadway structure which passed below a 20-m-deep operating underground subway station that was built in 1913. The innovative underpinning scheme used to support the subway station during construction resulted in the successful mining beneath the subway station with negligible vertical settlement. Two grouting galleries were carefully mined below the subway structure, and pre-grouting of the granulary, pervious glacial soils and weathered bedrock was carried out from these galleries. The reinforced concrete walls of the underpinning structure were constructed within three stacked drifts that were sequentially mined below each grouting gallery. After 11 cross adits were mined between the grouting galleries, cast-in-place post-tensioned girders that spanned between the stacked-drift walls were constructed to support the subway station. The stacked-drift walls also provided lateral support for the 22-m wide by 29-m long by13-m high opening beneath the girders.

Jan 1, 2001

By J. F. Havard

The enterprises based upon the industrial minerals are diversified in geologic habit, mining systems, processing techniques and marketing methods. Nevertheless, in 1972 these enterprises faced many of the same frustrations and hopes and knotty problems and crucial decisions. Volume and profits were generally improved but were uneven in extent and effect. The U.S. cement industry, for example, was unable to meet demand in major markets. It was constricted by a frozen low-level price structure, faced expensive pollution control measures and watched heavy imports penetrating its markets from several European nations, Mexico and Canada.

Jan 1, 1973

By H. P. Greenwald, Irving Hartman, H. C. Howarth

"INTRODUCTION A report of tests of seven small pillars formed from the Pittsburgh coal bed in the Experimental coal mine was given in Technical Paper 605 5/ Five additional pillars were tested between July 1939 and. October 1940. The data obtained, in the later tests permit an extension of the conclusions reached in Technical Paper 605, which appears to be important enough to the mining industry to justify a progress report that will explain briefly what it is and how it was obtained. Full detail of the tests will appear in a second technical paper, preparation of which is deferred so that results of pillar tests now under way my be included.DESCRIPTION OF TESTSExcept for minor improvements in operating details, the five additional tests were made as described in Technical Paper 605, pages 2 to 7. Briefly, the desired pillar was formed from the coal bed, by excavating a passage around it (no explosives were used), and enough material was removed from above to permit installation of the assembly used for applying pressure. Each pillar was tested resting on its original fireclay floor, which was restrained from lateral flow by a ring of concrete. Vertical and lateral movement of the pillars in two directions as measured carefully in all tests."

Jun 1, 1941

The banded iron formations "jasper bars," jaspilites, banded hematite quartzites or banded ironstones, etc., as they have. variously been termed in Western Australia, constitute one of the most striking features of the Pre-Cambrian in this State. They occur in at least two distinct divisions of the Pre-Cambrian, viz., in horizons interbedded with quartzites, shales and thin bedded dolomite in the N~llagine (Proterozoic) Series; and amongst the Older Pre-Cambrian rocks, associated with the metamorphosed sediments of the Jimperding-Chittering Series, the Yilgarn Whitestone Series and the Mosquito Creek Series, and interbedded with metamorphosed basic lavas, tuffs and sediments of the Older prenstone or Kalgoorlie Series.In the Hamersley Ranges in the north-west of Western Australia banded ferroginous cherts are well developed amongst the horizontal sediments of Nullagine Age. These iron formations have recently sprung into prominence as they have been found to form the host rocks for important deposits of· blue asbestos. They are closely comparable with the unique crocidolite-bearing banded ironstones of the Cape Province, South Africa, and have been described elsewhere in some detail by the writer. (1) t .The banded iron formations with which it is intended to deal principally in the following pages, form most abundantly in the Central and Eastern Goldfields of Western Australia where they form portions of the Older Greenstone or Kalgoorlie Series of auriferous rocks. In these regions their chemical inertness and physical hardness provide considerable resistance to the agents of erosion and consequently they frequently stand out in strong topographic relief in otherwise monotonously flat or gently rolling country. These banded-iron formations have proved of considerable direct economic importance in the goldfields and in other portions of the State because of thei!! associations with 'gold, iron -and to' a lesser extent, manganese; whilst indirectly because of their peculiar nature, form and topographic prominence, etc, they have been of tremendous assistance to the field geologist both in the practical application of methods of geological mapping and in the' elucidation of geological structures. Finally, they have recently acquired a new importance in the specialised search for ore-bearing lodes or for structural information over areas of soil-covered country, as their form and composition make them ideal subjects for the use of either electrical or m!1-gnetic methods of geophysical prospecting.

Jan 1, 1941

By Melvin I. Esrig

Lime Cement column stabilization of soft clay and sand in Salt Lake City, Utah and in San Francisco California is described and discussed. Stabilization permitted the construction, in a single stage, of a 14 m MSE wall on "medium" clay in Salt Lake City. It was used to mitigate the potential for liquefaction in San Francisco and to stabilize the Young Bay Mud beneath the BART extension to San Francisco Airport. These applications are described and the field measurements of performance are reported.

Jan 1, 2000

By A. W. Dougall, T. M. Mmola

"SynopsisThe global resources and commodities market has become highly competitive. While southern Africa’s abundance of minerals resources is still unrivalled, it has lost considerable dominance in terms of production output. The sustainability of southern Africa’s mining industry is increasingly becoming dependent on its ability to manage the performance of its operations well. A valuable tool for monitoring and managing performance is the use of key performance areas (KPAs) – which are those areas of performance that are reflected explicitly or implicitly in the vision and strategies of an organization and reflect the critical success factors of the organization. This paper is a review of key performance areas in the southern African mining delivery environment. The KPAs discussed in this paper have been identified by comparing KPAs of the several mining houses engaged in surface mining operations in southern Africa and then extracting those KPAs that are common to most of them. Although the authors support the view that each organization should develop KPAs to specifically fit its needs, the study reveals that five KPAs – safety and health, costs, product quality, fleet management, and delivery should form a default list that covers the key areas that any organization should consider when choosing KPAs. KPIs are those subsets of KPAs that we measure in order to manage KPAs.IntroductionThe global resources and commodities market has become highly competitive. While southern Africa’s abundance of minerals resources is still unrivalled, it has lost considerable dominance in terms of production output. The sustainability of southern Africa’s mining industry is increasingly becoming dependent on its ability to manage the performance of its operations well. A valuable tool for monitoring and managing performance is the use of key performance areas (KPAs), which are ‘those areas of performance that are reflected explicitly or implicitly in the vision and strategies of the organization’ (Barker, 1997). The terms KPA and KPI (key performance indicator) are often used interchangeably – whether correctly or erroneously is debatable. KPIs are ‘quantifiable measurements, agreed to beforehand, that reflect the critical success factors of an organization’ (O’Neill, 2007). Each KPA probably has multiple KPIs associated with it."

Jan 1, 2015

By W. L. Dare

This information circular is one of a series the Bureau of Mines plans to publish describing the methods and costs of mining uranium on the Colorado Plateau. The Temple Mountain mining district is unique among the uranium-producing areas on the plateau. This relatively isolated mining district is in Emery County, Utah, on the eastern flank of the San Rafael Swell, about 35 miles southwest of the town of Green River. The district lies just within the eastern escarpment of the San Rafel Reef - a rampart of rugged and tilted sandstone cliffs that encircles the highly eroded core known as the Sinbad Country. The presence of petroleum matter found associated with the ore deposits, the occurrence of uranium in various formations, and the structural deformation caused by collapsed features have aroused a great deal of geologic interest. Mine development on Calyx Flat is distinctive, in that the ore deposits are worked through 36-inch calyx-drill holes.

Jan 1, 1957

By K. C. Dean

During the course of the investigation of manganese mineral occurrences in the western United States, the Bureau of Mines collected several lots of ore' from properties in the vicinity of Winkelman, Ariz. As none of the ores would be marketable directly, an investigation was made to determine their amenability to concentration by ore dressing. The Geronimo group of claims is in Pinal County, 8 miles west of Winkelman, Ariz. The manganese oxides occur as cementing material in ore zones of conglomerate. Representative samples of a 2-ton lot of ore cut from outcrops of two lenticular deposits were laboratory-tested. Two 1-ton samples from the Benningfield property were similar in physical characteristics but differed in grade. This claim is 11-1/2 miles south of Winkelman and about 1 mile west of the San Pedro River on the south side of Putman, Wash. The manganese minerals occurred as nodules and lenses, replacing limestone, in a capping over a dark, igneous dike. The North Star group consists of five claims on the west side of the San Pedro River 14 miles south of Winkelman. The ore consists of a low-grade, manganese oxide-calcite occurrence interspersed with stringers of higher-grade material and is present as filling in a fissure zone in porphyry. Two samples were obtained by the examining engineer; one sample represented run-of-mine material, the other represented ore from the vein that could be hand-sorted or selectively mined.

Jan 1, 1952

By Jiwei Duan

The energy transferred from a hammer to the pile top is considered as the effective energy in this paper. The effective energy is related to the pile dimensions, soil and pile-soil interface properties. This relation may be expressed as an equation based on the dimensionless theory. The relationship between pile capacity and effective energy was studied by performing a series of wave equation analyses using a commercial software called GRLWEAP (Wave Equation Analysis Program) by GRL Engineers, Inc. The results show that the pile capacity increases with the blow count when the effective energy is constant, however, it has a little change as the blow count is over 100 blows per foot. The pile capacity decreases as the ratio of pile penetration depth to pile diameter increases if the effective energy is constant. The pile capacity will increase as the pile diameter and wall thickness increases if the effective energy is constant. The pile stickout (pile length above the ground surface) does not have a significant effect on the effective energy and may be neglected. Curves for pile capacity versus effective energy are presented to be used for preliminary hammer selection according to effective energy and hammer efficiency. Finally, a case from PDA testing was studied. Measurements of the effective energy and pile capacity by CAPWAP were presented and compared with the results by GRLWEAP.

Jan 1, 2006

An extensive laboratory grinding study was carried out on a magnetite ore in order to assess the grinding behaviour of magnetic concentrate and tail from low intensity magnetic separation (LIMS).The test work involved Bond ball mill testing, rod milling, low intensity magnetic separation (LIMS), and batch ball milling down to product sizes of around P80~25 microns. A total of 18 Bond tests and over 150 batch grinding tests and sieve sizing were carried out. Throughout the grinding tests, power draw was continuously monitored. The relationship between the grinding energy and product size was analysed using the conventional energy-size concepts. It was found that the Rittinger equation fits the experimental data well. However, Bond?s equation does not fit the experimental data well, and therefore a modified Bond equation was developed. Differences in grinding properties between the magnetic and non-magnetic component were analysed and compared to the bulk ore. It was found that grinding properties differ significantly and therefore separate grinding test work may be required for each grinding step in the magnetite ore beneficiation flowsheet. Keywords: grinding, iron ores, particle size, modelling.

Jan 1, 2010

By Kay E. Goldberg

The Bureau of Mines conducted a study to develop and evaluate a training workshop for mine safety training personnel. The workshop was based on the Instructional Development Institute (IDI) which has been used for nearly ten years to train educators and administrators in the application of a nine-step model for defining, developing, and evaluating instruction. The Mining Instructional Development Institute (MIDI) was developed by investigators at the University of Southern California as a two-phase project. Phase I involved the modification of the six-day IDI program (including audiovisual presentations, workbooks, games, and exercises) for use by mine safety trainers as a workshop lasting three and one-half days. Phase II involved the evaluation and validation of the prototype MIDI workshop by means of a two-stage jury of experts and a prototype field trial. On the basis of data collected in the validation process it was determined that the institute provided an effective and useful method of instruction in mine safety training and that the institute would be especially valuable for mine safety training administrators and supervisors.

Jan 1, 1980

By Steven D. Dapp

The use of base grouting (tip grouting) to enhance the axial capacity of drilled shaft foundations can achieve improvements in economy and reliability for many types of projects and soil profiles. Recent experiences on a range of different construction projects in the Southeastern U.S. illustrate the most attractive opportunities for utilizing this technique and some limitations of the method. The quality assurance provided by measurements obtained during post grouting the pile toe is another important aspect favoring its use; the base grouting is shown to identify weaker piles and provide a means of remediating some deficiencies so that increased foundation reliability is achieved. This paper provides an overview of the methods used to evaluate and design for base grouted shafts along with lessons learned from several case histories.

Jan 1, 2006

By A. T. Iannacchione

The Bureau of Mines established geologic factors affecting the mining of the Lower Kittanning coalbed to aid in coalbed minability studies and examined the occurrence of "wants" (places where coal is missing) and types of unstable roof rock strata. Trends established from mapping, including prediction of areas of high methane emissions, were extrapolated to unmined areas. 'Wants' in the coalbed are of two types: Erosional and depositional. Erosional features occur where north-south-trending sand-filled channels cut into the coalbed. Variations in depositional environments have caused the coalbed to "split" into several thinner units. Slickensides, commonly indicative of unstable roof, are adjacent to and on the underside of sandstone channels; they were caused by differential compaction and by soft sediment sliding along the contact between the sandstone and adjacent shale. The frequency of unstable roof also increases where the interval between the Middle and Lower Kittanning coalbed is less than 30 feet. The zones of weakness at the contacts above and below the Middle Kittanning coalbed are the controlling factors for unstable roof in these strata. Methane emissions from the coalbed are controlled primarily by depth, fracture permeability, and rank of coal. Local geologic factors are coalbed thickness, associated rock strata, structure, and proximity to outcrop.

Jan 1, 1979