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By S Novak

A world-class example of sustainable development in practice, the Local Resource Development Initiative (LRDI) grew from agreements between the Ambatovy nickel mine developers and the Government of Madagascar. A program of training and community development, the LRDI aims to maximise local benefits by optimising the integration of local resources during the construction period of the mine. By local resources, we mean the local labour force as well as local goods and services. Begun in 2007, the foundation of the LRDI is to integrate local resources into the mining project and where gaps are identified, design and implement training, mentoring and other programs to fill those gaps. The principal accomplishments are: the establishment of training centres that trained over 4000 people in little over one year, 96 per cent of whom hired to work at the mine; a support program for local micro, small and medium enterprises that has led to the award of 65 contracts for goods and services with training and mentoring of over 100 local businesses; and a number of special projects that have, among other results, strengthened local agricultural development and created employment for young people. The LRDI provides unique insights into key indicators and lessons learned to strengthen the social and economic sustainability of mining projects in developing countries. The paper will discuss these in terms, among others, of: the importance to project success of upstream planning to address socio-economic issues; the role of civil society and other local partners to strengthen and expand sustainability outcomes, and to spur governments to demand that major projects promote economic and social sustainability; and the integration of mine sustainability with sustained regional social and economic development.

Jan 1, 2009

By J. F. Reddick

The South African coal mining industry is currently disposing of about 10 million tons of ultra-fine coal (<150 µm) per year. Once discarded, these sulphur-containing ultra-fines contribute to several environmental problems. As part of a project initiated by the Water Research Commission to investigate the use of Cleaner Production (CP) in the mining industry, a study was carried out to determine whether a CP approach could be used to identify opportunities to reduce this coal waste, and to determine which of these opportunities would be most feasible. In order to do this, a CP assessment was conducted at three case study collieries in the South African Witbank coalfield. Mass-balancing and sampling, followed by laboratory characterisation tests and site surveys, were used to determine the quantity, quality and sources of the ultra-fine coal at the three collieries. Literature reviews, brainstorming sessions and interviews then followed to generate the CP options. An environ-mental, economic and technical feasibility assessment was then prepared for each option, to determine the most viable interventions for implementation. A number of opportunities were identified through the assessment. By preventing coarser coal from being discarded with the ultra-fine coal, the quantity of coal disposed of could be decreased at all three collieries, and by up to 24% in one case. Increasing the crusher top size would reduce the amount of coal that is milled to less than 150 µm, so that less is wasted. The ultra-fines that have already been disposed of on slurry dams can be completely reclaimed and converted into a valuable product, which can be sold as power station feedstock. The newly processed ultra-fines could be beneficiated using flotation and exported together with the coarser coal. The results of the assessments thus suggested that workable CP opportunities to reduce ultra-fine coal wastage exist at the sites investigated, and that their feasibility is colliery-specific. The associated financial benefits of the proposed options suggested that CP is a realistic approach to addressing environmental problems. Keywords: Cleaner Production; coal mining; coal-washing; ultra-fines

Jan 1, 2007

By J. Daraisme

Société le Nickel (SLN) exploits the Dôme lateritic nickel orebody at its Tiébaghi operations in New Caledonia. The site geology has an obvious bearing on recovery and metallurgical performance, and the controls are extremely complex at all scales: lithology, oxidation-reduction conditions, mineralogy, and multivariate geochemistry. In that context, establishing an adapted recoverable resource estimation method that is efficient and transparent proves an interesting challenge. The method must address the key notions of: ? Support effect: the exploration data-set can only warrant the estimation of large panels 20×20×3 m3, which are much larger than the selective mining units (SMUs) of 5×5×3 m3 ? Information effect: the selection at production stage uses estimates based on information much denser than that available for mine planning. The problem is rendered more complex in this type of deposit by the fact that the additive variables used for any estimation process (metal accumulation and ore tonnage) are not the ones used to establish the selection at mining stage (i.e. the nickel grade of SMUs, which is the ratio of accumulation on tonnage). Eventually, the selection criteria involve not only Ni grades but also other constituents such as Al2O3, Fe2O3, MgO, and SiO2. The solution presented in this paper is the construction of a platform of SMU multivariate simulations in the saprolitic horizon, together with efficient post-processing aimed at producing the multivariate recoverable resource estimates. The efficiency constraints imposed by the number of blocks to be simulated (1.5 million) lead to resorting to direct block simulations. The underlying multivariate discrete Gaussian model (DGM), the validity of which is tested beforehand, is put to good use to mimic the selection process at the mining stage, by offering the ability to simulate in each block a composite value located at random within the block. Finally, the paper presents the application of a scenario reduction algorithm to pick a representative subset of a few simulations to help appraise the risk attached to the downstream phases (reserve optimization, mine sequencing) of the project. The implementation presented here is for the first generation of the Scenario Reduction plugin built in Isatis software, where measuring the distance between the initial set of scenarios and the reduced set is based on Ni quantities only. Research is under way to adapt the measure to the true multivariate nature of the problem.

Jan 1, 2014

By B. W. J. van Rensburg, M. J. Schmidt

Bulk materials handling systems are extensively used in the mining and minerals industry, where a fairly high incidence of structural failure is experienced, notwithstanding design compliance with appropriate standards. A number of case studies are explored to demonstrate how insufficient controls or protection systems have contributed to structural failures on mobile bulk handling equipment. The importance of design integration across engineering disciplines is highlighted. The revision of ISO 5049-1 (1994) is proposed to provide specific rules and guidelines pertaining to machine protection systems. It is further recommended that the structural design engineer of the original equipment manufacturer(OEM) fulfils a more prominent role during the final acceptance and handover of mobile bulk handling equipment, with specific reference to protection systems.

Jan 1, 2015

By S. J. Page, R. A. Jankowski, J. A. Organiscak

The U.S. Bureau of Mines investigated the relationship of bituminous coal seam parameters and the amount of airborne respirable dust generated at longwalls. Dust and coal samples were obtained from 20 longwalls operating in geographically representative coalfields throughout the United States. Statistical analyses of coal seam parameters and airborne respirable dust measurements indicate a likely causal relationship between seam type and respirable dust. Low-ash, high-volatile coal seams were associated with higher airborne respirable dust levels. A negative linear correlation (significant at the 95-pct confidence level) was observed between the seam&apos;s ash content and airborne respirable dust, explaining up to 18 pct (R2 = 0.18) of headgate dust level variation and up to 15 pct of tailgate dust level variation. Volatile matter was found to have a positive linear correlation with tailgate dust level, explaining 16 pct of the variation. Further data examination indicates that these relationships with dust are most likely nonlinear, because of improved R2 values over the linear correlations. However, a notable portion of longwall dust production is influenced by other operational parameters, so additional research under more controlled conditions is needed to determine the seam&apos;s causative functions.

Jan 1, 1992

By Ed D. Thimons, Douglas E. Pollock, Andrew B. Cecala, Gregory J. Chekan, Jay F. Colinet, John A. Organiscak

Researchers at the Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) work to reduce respirable dust exposures in mining operations. One focus of this research is silica dust control for surface and underground operations in the metal/nonmetal mining industry. PRL researchers analyze dust sampling results from the Mine Safety and Health Administration (MSHA) to identify high-risk occupations to guide research efforts. Research is then conducted in an effort to improve existing technologies and/or develop new controls for reducing worker exposure to airborne silica dust. During the last few years, PRL researchers have conducted research related to the following goals: improving protection provided by enclosed cabs on mobile surface mining equipment, reducing dust generation from surface drills, reducing dust levels in iron ore operations, and developing a new method to clean dust from workers’ soiled clothes. A description of each of these controls and subsequent dust reductions quantified through site surveys will be provided.

By A. C. du Preez

The separation of nickel and cobalt from calcium, magnesium and manganese by solvent extraction using synergistic mixtures of carboxylic acids was studied. Addition of certain viable synergists to commercially available tertiary branched carboxylic acids, such as Versatic 10 (Shell) or Neodecanoic acid (Exxon), produced large synergistic shifts (?pH50) in the pH50values for nickel, and small antagonistic shifts (negative ?pH50values) in the extraction of calcium. Under the initial test conditions used (0.50 M each of Neodecanoic acid and the Mintek synergist, in xylene) a large separation (pH50Ca? pH50Ni= 3.09 pH units) between nickel and calcium in their extraction from 1.00 M sodium nitrate solutions was obtained, compared with only 1.11 pH units in the absence of the synergist. The selectivity series for the extraction of divalent base metals from 0.333 M sodium sulphate solutions by 0.50 M Neodecanoic acid and 0.25 M of the Mintek synergist in C12-C13aliphatic diluent was found to lie in the order (with pH50values in parentheses): Cu(3.42) > Ni (5.08) > Zn (5.58) > Co (5.73) > Mn (6.62) > Ca (7.48) >Mg (8.25). In batch counter current experiments, a simulated leach liquor containing (in gL-1): Ni 5, Mg 5, Mn 2, Co 0.5, Ca 0.5, Cu 0.1and Zn 0.1 was contacted with the mixed extractant in three stages at unit phase ratio and an equilibrium pH of 5.9. The recovery of nickel was 99.9 per cent and that of cobalt was 84.7 per cent, whilst the co-extractions of manganese, calcium and magnesium were 2.7,1.5 and 0.04 per cent, respectively. The recovery of cobalt can be enhanced by employing a slightly higher pH, although this will also increase the extraction of manganese, calcium and magnesium somewhat. Nearly quantitative stripping (99 per cent) of nickel from the loaded organic phase was achieved in a single contact at an organic-to-aqueous phase ratio of 4 using a simulated spent electrolyte containing 39 gL-1sulphuric acid and 33 gL-1nickel,thereby producing an ?advance electrolyte? containing 57 gL-1nickelat pH 3.5. Loading of acid into the organic phase was very slight, amounting to only 0.002 M H+in contact with the above-mentioned spent electrolyte. Keywords: solvent extraction; synergism; nickel; calcium; carboxylic acids.

Jan 1, 2004

By John Fritz

MEMBERS of the American engineering societies who were in London and Paris during the last days of. June and early July were present at many interesting gatherings. The official delegates of the Founder societies were the specially honored guests of the foreign engineering societies, but other American engineers took part in the meetings. The members of the delegation were: Arthur S. Dwight, Charles F. Rand, William Kelly, representing A. I. M. E.; Ambrose Swasey (general chairman of deputation), Ira N. Hollis, Jesse M. Smith, representing A. S. M. E.; F. B. Jewett, A. E. Kennelly, G. O. Squier, representing A. I. E. E.; Charles T. Main, Robert A. Cummings, John R. Freeman, D. C. Henny, representing A. S. C. E.

Jan 1, 1921

By Satyajit Vaidya, Rudolph Frizzi, Luis Berroteran

This paper presents design and construction challenges associated with a high-capacity rock-socketed drilled pile foundation system for a 60-story building recently constructed in an urban environment. The site is in very close proximity to surrounding 1-to-6-story buildings and a commuter rail subway tunnel structure. High compression, uplift, and lateral loads imposed by the tall, slender tower constructed over a relatively small site footprint posed a significant design challenge due to the close proximity of the subway tunnel and other structures. Construction challenges included those associated with advancing the drilled pile casings through overburden materials using internal flush method mandated by the Transit Agency, advancing the casings through very dense glacial till materials encountered above top of rock, and drilling rock sockets in variable rock conditions. This paper provides a brief overview of the site and subsurface conditions, and discusses the resulting design and construction challenges for the drilled pile foundation system and how they were addressed. SITE AND SUBSURFACE CONDITIONS The 8,350-square-foot site is located in a busy neighborhood in downtown New York City (NYC). Buildings neighboring the site are supported on shallow foundations, and their basements extend about 15 feet below the sidewalk level. A NYC-Landmarked building is located within a NYC Department of Buildings (DOB)-designated 90-foot influence limit from the Project site. NYC Transit Authority (NYCTA) subway tunnel and station structures are located in close proximity to the Project site. The subway tunnel structure extends about 50 to 55 feet below the sidewalk level. Although the upper portion of the tunnel structure is about 13.5 feet away from the site property line, the lower portion is only about 1 foot away from the property line. A site location plan is presented as Fig. 1. Geotechnical borings revealed subsurface conditions generally consisting of successive strata of surficial fill, sandy and silty soils, and glacial till (predominantly consisting of cobbles and boulders) overlying mica schist bedrock. A generalized subsurface profile is presented in Fig. 2. The surficial fill stratum was about 10 to 23 feet thick, and generally consisted of loose to medium dense sandy soils with varying proportions of silt, gravel, and miscellaneous debris such as brick. The underlying sandy and silty soil stratum was about 60 to 79 feet thick and generally consisted of loose to medium dense inter-bedded layers of fine to coarse sand, silty fine sand, and silt. The underlying glacial till stratum was about 26 to 70 feet thick and generally consisted of cobbles and boulders embedded in a very dense soil matrix. Top of bedrock was encountered in the borings about 110 to 150 feet below sidewalk level. Groundwater level was measured at about 30 feet below sidewalk level.

Jan 1, 2018

Extraction of copper from a chalcopyrite concentrate by means of a cupric chloride leach is described. Initially the concentrate is mixed with sulphur in a 9: 1 ratio, and heated to 350-400&#176;C. This converts the chalcopyrite into more readily soluble sulphides, while the iron rejected from the chalcopyrite is transformed to pyrite, which is insoluble in the leach solution employed. A two-stage countercurrent leach using a leach solution of 1 M cupric chloride, 3.5 M sodium chloride, and 1 M hydrochloric acid extracts 98 per cent of the copper, if conducted at 105&#176;C. Iron extraction is relatively low, the mole ratio of iron to copper extracted being 0.17, compared to 1.0 for unreacted chalcopyrite. After dissolution, copper can be recovered by electrolysis, cupric chloride leach solution being regenerated at the anode.Electrolytic power requirement is low, being approximately 0.5 kWh per kg of copper. The sulphur and, most of the iron entering as feed are rejected from the process in the form of pyrite, which remains in the leach residue.

Jan 1, 1974

By John P. Davis

The use of conventional, circulatory air rotary and fluid rotary, cased and uncased drilling methods in the vicinity of sensitive infrastructure can have deleterious effects on the ground conditions surrounding and supporting structures and the structure itself. Furthermore, the use of these conventional methods offers the engineer or contractor little information about the condition of the subsurface during geotechnical applications. Conversely, sonic drilling measurements and samples can be used to evaluate actual conditions during the progress of exploration and construction across a given site. This paper will discuss the history and properties of sonic drilling and explore case histories of geotechnical applications for the advancement of boreholes within vulnerable structures and on sensitive sites for several recent infrastructure projects ? a tunnel and railroad project, a dam grout curtain project, a bridge micropile exploration project and a tunnel instrumentation project. Project summaries will discuss the advantages realized when the application of sonic drilling techniques demonstrated superior accuracy, quality control, efficiency, productivity, penetrability, waste minimization and adaptability when drilling adjacent to or within existing infrastructure. Finally, the discussion will address the current testing and application of sonic drilling to the installation of micropiles, earth retention anchors, grout injection and instrumentation installation where the quality control benefits provided by the inherent soil cores, measurement while drilling systems, accuracy and non-destructive production drilling features will be advantageous.

Jan 1, 2006

By Robert S. Warfield

Eight samples of high-volatile bituminous coal, each large enough for a study of its coking properties by the Bureau of Mines, were obtained from a location along the Kukpowruk River, Arctic Northwestern Alaska. Bench scale and pilot plant carbonization studies with several patterns of coal blending were conducted. The data from these tests were compared to data from similar tests on a coking blend used by the Kaiser Steel Corporation at Fontana, Calif. The majority of the samples representing the 20-foot seam was found to have significant coking properties, and produced coke approaching metallurgical quality when blended with selected coking coals. Although oxidation effects were evident in the samples representing upper portions of the seam, it appears that the whole seam could be used.

Jan 1, 1966

By H. Y. Sohn, Hang Goo Kim

Computer simulations were carried out using calcium ferrite slags containing 25 wt% CaO, and the results compared with those obtained using fayalite slags. There was little difference in overall elimination of Pb and Bi, but elimination of Sb and As was much lower with calcium ferrite slag. When calcium ferrite slag is used only in the converting stage and fayalite slag in the smelting stage, as in the Mitsubishi process, the contents of Sb and As in the blister copper can be kept to reasonable levels. This allows advantage to be taken of the considerably higher iron oxide-holding capacity of calcium ferrite slag than of fayalite slag at the high oxygen potential under converting conditions, thus preventing precipitation of magnetite. Satisfactory agreement was obtained between predicted values and observed data from a Mitsubishi converter

Jun 18, 1905

By S. M. Bradshaw

The principles of microwave heating are discussed with reference to dielectric properties, heating phenomena and microwave equipment. Microwave regeneration of granular activated carbon for the carbon-in-pulp process is examined on a laboratory scale, with special attention being given to highlight the problem areas and specific considerations related to microwave heating. Results indicate that microwave regeneration of carbon with 40% moisture on a wet basis by heating to 650°C with steam addition regenerates the carbon to virgin carbon activity levels but with a higher abrasion resistance. A preliminary economic assessment showed that the capital cost for 120 kg/h microwave unit would be R540 000 with an annual operating cost of R 320/t carbon. These figures yield a return on investment of 12%. The aim of this paper is to provide an introduction to microwave heating and to illustrate its application to the microwave regeneration of granular activated carbon for the carbon-in-pulp (CIP) process.

Jan 1, 1998

By A. Broussaud

The paper describes the advanced grinding control system implemented at Newmont Ahafo gold mine, Ghana in 2009 and 2010. It shows how the different components of the Advanced Process Control (APC) system cooperate for increasing plant performance. The SABC circuit processes hard rock from different pits mixed with a variable proportion of oxides. The control strategy is designed to address specific disturbances, including start/stops of pebble crushers, unavailability of oxides, changes in rock size distribution resulting from segregation in the stockpile, and changes in ore type and hardness. The system consists of an expert system per se with extensive use of fuzzy logic, supplemented by an online dynamic model of the process used as a soft sensor, a VisioRock? rock size measurement system over SAG mill feed before addition of recycled pebbles, and an AudioMill? system to analyze the SAG mill sound and detect impacts on liners. All these components are embedded in the same OCS© software platform, which, among other benefits, makes it easy to support the entire system remotely. The paper details the physical constraints and the variables that are manipulated. It describes the control strategy and the contribution of each component of the system. It also describes the project implementation and the performance of the system. In addition to a strong involvement and support of management, the very good acceptance of the operators has been facilitated by the remote access system that made it possible to immediately modify the system each time it was needed during the baby sitting phase. The system made it possible to increase gold production significantly through increases in tonnage and recovery thanks to a better control of the grind size through a stabilization of the secondary ball milling circuit and an improvement of the operating conditions of the classifying cyclones.

Jan 1, 2012

By AIME AIME

ARRANGEMENTS for the Annual Meeting of the Institute were well advanced at the end of December as the following program will show. Heretofore this has been printed separately, but its inclusion in the Annual Review issue of MINING AND METALLURGY will, it is hoped, make it more easily available for reference until the final program is issued, which will be distributed at the meeting. Added details will appear in the February issue. Last year&apos;s meeting drew a record crowd of over 2300 which should be exceeded this year. Early reservations at the headquarters hotel, the Waldorf-Astoria, or any other convenient hotel are desirable, as are prompt reservations for the Annual Dinner. No one need worry about too much speechmaking this year, for the honors will be awarded and accepted in a few words instead of a few paragraphs, in seconds rather than minutes.

Jan 1, 1939

By Gary W. Krantz

Fibered, portland-cement-based gunite products were applied in the Bureau of Mines Lake Lynn Laboratory Experimental Mine using a variety of pneumatic guns and gunning crews, The demonstrated wet-mix (with silica fume), dry-mix, and surface bonding products were sampled by the Bureau and subjected to a suite of engineering analyses. Gunite flexural and compressive strength, rebound, permeability, porosity, dust loading, shooting rate, crew requirements, and cost factors were evaluated. Steel, fiberglass, or polypropylene fibers were contained in all but two of the gunires tested. Both Bureau and private testing laboratory analyses are provided for some products. Electron probe micro-analysis and X-ray diffraction analysis were performed on the silica fume fraction of the wet-mix gunite to characterize the dust. Aggregate size fraction distribution analyses were performed to provide strength relationships. Results indicate that all of the commercially available fibered-gunite materials tested can provide beneficial sealant, spall prevention, or roof stability control attributes for underground mining environments when applied by an experienced crew using a well-maintained gun, in accordance with product manufacturers&apos; recommendations and when used for the designated purpose.

Jan 1, 1984

By K. L. Morton

Groundwater and associated pore pressure represent elements that can have a negative impact on surface mining and slope stability. Groundwater flow and deformation within a slope influence each other. An increase in pore pressure will result in a decrease of effective stress; and conversely, if the pore pressure decreases, the effective stress increases. Slope analysis and slope design calculations require good information on pore pressure distribution around an open pit excavation. Until recently very little pore pressure data were available and assumptions had to be used. Location and design of measuring points depend on geological and structural setting, geotechnical domains and practicality. Good planning and the use of sensitive point piezometers to measure in situ pore pressures means that real-time data can be collected and used for the construction of flow nets, the determination of pore pressure distribution around an open pit mine, the validation of the dewatering/depressurization requirements, the calculation of the efficiency of the dewatering system and finally the use of pore pressure data in slope stability analysis. The recommended layout for a monitoring system, types and design of piezometers, data collection and use of the pore pressure data are presented.

Jan 1, 2008

By M. Bwalya, L. Mabokela, L. C. Woollacott

This paper presents a study on the ability of the King stratification modelto describe density stratification patterns that are achieved under idealizedconditions. Tests were conducted in a batch jig using artificial particles inseven density classes. All particles in a density class had essentially thesame density, size, and shape. Tests were conducted for particle systemsinvolving from two to seven components. Good agreement was obtainedbetween measured and modelled data to an extent that gave strongendorsement of the mathematical appropriateness of the core equation inthe King model. Somewhat ambiguous results were found with regard toclaims about the independencies of the single experimentally-determinedparameter required by the model.

Jan 1, 2015

By S. Kouniali

Experience with knowledge-based systems for Layout planning and roadway support dimensioning is on hand in European coal mining since 1985. The systems SOUT (support choice and dimensioning, 1989), SOUT 2, PLANANK (planning of bolt-support), EXOS (layout planning diagnosis. 1994), Sout 3 (1995) have been developed in close cooperation by CdF1. INERIS2. EMN3 (France) and RAG 4, DMT5, TH - Aachen6 (Germany); ISLSP (Integrated Software for Layout and support planning) development is in progress (completion scheduled for July 1996). This new software technology in combination with conventional programming systems. numerical models and existing databases turned out to be suited for setting-up an intelligent decision aid for layout and roadway support planning. The system enhances reliability of planning and optimises the safety-to-cost ratio for ? deformation forecast for roadways in seam and surrounding rocks, consideration of the general position of the roadway in the rock mass (zones of increased pressure, position of operating and mined panels). ? support dimensioning ? yielding arches, rigid arches, porch sets, rigid rings, yielding rings and bolting / shotcreting for drifts ? yielding arches, rigid arches and porch sets for roadways in seam ? bolt support for gateroads (assessment of exclusion criteria and calculation of the bolting pattern) ? bolting of face-end zones (feasibility and safety assessment, stability guarantee).

Jan 1, 1996