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By Alastair Grogan, Ron Elliott, Dale MacLean

Blasting for armour stone presents many unique challenges. Often, blasters get themselves into trouble when they assume that they can simply modify a production blast design to produce the required fragmentation size. They bid on the project using typical production blasting costs, and then find that they cannot produce the required fragmentation size and quantity with an acceptable waste factor. This paper outlines industry best practice guidelines for the production of riprap or armour stone. The paper examines the importance of initial geological mapping to determine the average in-situ block size, and the advantages to be gained from working with the geology to maximize production of the required block sizes. The paper also outlines the importance of proper explosives selection as well as blast designs that are unique to the production of riprap. The paper reviews challenges and experiences realized from multiple projects in differing rock types.

By Janne P. Isohaka, Anssi M. Laaksonen

"Abstract In Scandinavia the use of steel pipe piles in bridge foundations started in the mid-1980s and has increased steadily since. As the piles driven in soft soils are slender, they can fail by buckling. Buckling usually requires taking into account the second order effect in structural and geotechnical design.The purpose of this paper is to derive formulas for demonstrating the theory behind the formulas given in literature for the second order effect of initially bent piles.IntroductionIn Scandinavian countries solid bedrock usually lies at moderate depth. If the bridge site is in an area where the soil above the bedrock is soft, the bridge is usually founded on end-bearing piles resting on the bedrock.The main purpose of the piles is to transfer axial forces into bearing soil. Like columns, piles can lose their stability by buckling when surrounded by soft soil. When axial compression on a slender, initially straight, pile reaches a particular value called the critical load, the pile is subjected to lateral deflection and loses stability. The soil around the pile suffers a corresponding deformation. This soilstructure interaction increases the critical load compared to a pile without surrounding soil.It is very unlikely that piles are ideally straight. Initial curvature along with curvature and deviation caused by the installation of piles causes bending moments to the pile when normal force is applied. These lateral displacements increase when normal force increases. This increase of moment is called asecond order effect.Eurocode and literatureEurocode 7 includes guidelines for the design of piles (Eurocode 3, section 5 includes design of steel piles). However, there are no clear guidelines for considering the second order effects related to piles surrounded by soil. Eurocodes advise doing structural design of piles the same way as in the case of columns. With columns, the second order effect is taken into consideration by multiplying the first order moment with the factor shown below (SFS EN-1992-1-1, 2005):"

Jan 1, 2014

The panic bars (and associated linkages and electrical circuitry) that are defined in this document are a machine operator-actuated control for the emergency deenergization of the tram motors on self-propelled, electric and diesel face equipment; including haulage equipment such as shuttle cars. There are nine basic types of panic bars (and several variations) that are recommended in this document, but all of the panic bars are characteristically of the ?fire door? type that is frequently encountered on outside exit doors of many public and some commercial buildings. It is also the intent of the following panic bar designs that, when emergency brakes are added to the face equipment machinery for which they are required, that they be designed and hooked up so that actuation of the panic bar will result in automatic application of the emergency brakes (immediately following the deenergization of the tram motors). The following panic bar design requirements are a restatement of the proposed requirements defined in the Federal Register, requirements cited in "Guidelines for the Design and Installation of Devices for Deenergization of Self -Propelled Electric Face Equipment/Automatic Emergency Brake s II by C. E. Lester and J. D. Greenhalgh of MESA, and Bendix recommendations that were formulated as a result of discussions with personnel at the various machine manufacturers and underground coal mines that we surveyed, discussions with G. L. Judy (our consultant), etc:

Jan 1, 1974

The paper provides a brief review of a multivariate uniform conditioning and a localized multivariate uniform conditioning (LMUC) technique, and presents a production reconciliation case study based on a porphyry copper-gold deposit in Peru. The reconciliation study compares the longterm LMUC mineral resources model (typical of new mining projects, which are invariably based on drilling data on a relatively large grid) to the corresponding production blast-hole grade control model, as well as the final plant production.

Jan 1, 2014

By Nathan Fernandes Ignácio, Filipe da Silva Siqueira, Weslley Luiz da Silva Assis, Paulo Rangel Rios

As pesquisas em transformação de fase ganharam novos horizontes a partir dos recentes estudos de Rios & Villa. Eles desenvolveram inéditos modelos analiticamente exatos a partir da geometria estocástica. Estes modelos são exatos para resoluções de problemas de nucleação e crescimento não homogêneos. O presente trabalho visa o estudo da nucleação em clusters, cuja cinética de transformação de fase sólido-sólido diverge consideravelmente daquela prevista pelo modelo JMAK. Nesse tipo de nucleação, os núcleos não estão homogeneamente dispersos na matriz, mas concentrados em regiões preferenciais chamadas clusters. Um dos principais parâmetros dessa nucleação é o número de clusters na matriz. Nesse trabalho, utilizando um modelo estocástico baseado na teoria do Cone Causal, foram simuladas reações de nucleação e crescimento que ocorrem especificamente em forma de clusters esféricos. Foi possível analisar o efeito que a variação do número de clusters provoca na cinética de transformação de fase e comparar os resultados obtidos com o modelo de Rios & Villa. Por meio dessa comparação, é possível observar que o modelo analítico corroborara com os resultados numéricos. Como conclusões principais tem-se que quanto menor o número de clusters, mais lenta é a reação de transformação de fase e que a microestrutura gerada possui características próprias e os resultados podem ser interpretados de maneira errônea se a presença dos clusters não for propriamente detectada.

Nov 7, 2019

By Henrique Dias Gatti Turrer

O complexo Minas-Rio da Anglo American iniciou suas operações em agosto de 2014. A usina de filtragem produziu, em 2016, cerca de 15 milhões de toneladas secas de concentrado. O minério, explorado no município de Conceição do Mato Dentro (MG), passa pelas etapas de cominuição, classificação, concentração e separação sólido-líquido antes de ser bombeado por 529 km até o município de São João da Barra (RJ), onde é filtrado, estocado e embarcado para exportação. Quatorze filtros cerâmicos, com 144 m² de área de filtragem cada um, são responsáveis pelo último processo de produção do pellet feed. O início de operação foi marcado por um desempenho muito aquém do planejado. Diversos tipos de avaliações, como análises em microscópio ótico e contagem de bactéria, foram conduzidas e mostraram que o entupimento precoce dos poros do meio filtrante era o responsável pelo problema. Foram identificados 4 principais responsáveis pelo entupimento: material orgânico, sulfato de bário, partículas de concentrado de minério de ferro e óleo. Amostras de placas cerâmicas foram testadas em laboratório com diferentes reagentes para a limpeza dos poros entupidos. Análises químicas na solução resultante dessa lixiviação e/ou análise em microscópio dos corpos de prova indicavam a eficiência do reagente testado. Os mais promissores foram testados industrialmente. Por fim, o estabelecimento de uma nova rotina de limpeza das placas gerou uma melhora significava do desempenho da filtragem.

Oct 30, 2017

By Bruce Maxwell

The deformation modulus of coal mine pillars theoretically can be reduced by drilling holes in advance of the mining face. This reduction of modulus along the edge of the pillar has the effect of decreasing the stress concentration in the roof; control of roof caving is thereby predicted. Initial field work indicated that a high horizontal stress field existed at the field test site: Subsequent field work was undertaken to confirm the high horizontal stress field and to attempt to relieve the horizontal stress in the immediate roof. A method of softening pillars in conjunction with normal mining activity was developed. Instruments to measure horizontal roof strain, roof parting, roof tilt at the rib, and changes in vertical and horizontal stress in the roof and in the coal were used. These instruments were installed in both softened and unsoftened entries and in locations to indicate the effect of vertical slots in the roof. Significant stress reduction due to pillar softening was indicated, but the effect of this reduction on roof stability was not established. The vertical roof slots relieved the horizontal stress in the immediate roof very effectively, and observations of roof conditions indicated that the slots definitely improved roof stability.

Jan 1, 1977

By Edward G. Cunney

[Track in underground bituminous coal mines was investigated and technology has taken from other industries in order to Main information on conditions that impair the safety and efficiency of the track and to develop guidelines ad useful information on the constriction, inspec¬tion and maintenance of mine track. Volume l contains information oil the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features such as gage, descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. As a research product, it 0005 nut repeat the summary or derivations. Volume 5, Inspection Handbook, summarizes recommended standards and procedures from Volume 2 and provides related information for read: refer¬ence by inspectors in tin mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.]

Jan 1, 1977

By Douglas H. Brown

Cadmium and other 'minor' metals in Canada tend to remain inconspicuous given the prominence of the country's massive production of other minerals. This same reality is reflected in the accuracy and deficiency of quantitative data concerning the sources of supply and demand for these metals. It is the intent of this paper to identify the nature of some of these difficulties and to reconstruct a more accurate description of Canada's production and consumption of cadmium, based on the results of recent surveys undertaken by the Mineral Policy Sector of Energy, Mines and Resources Canada and Noranda Sales Corporation Ltd.

Jan 1, 1978

By Robert L. Morris

A new concept of roof support by "sonic pin-setting" is introduced. Initial experiments indicate that this method could introduce tremendous benefits for the coal mining industry by making roof-bolting a faster, safer, and more economical operation. A theoretical model is presented for describing the process and an experimental machine was built. The present testing results are included.

Jan 1, 1977

Coal, America's most abundant fossil fuel, is expected to play a key role in our pursuit of energy independence. A substantial increase in coal exploitation will be required if we are to fulfill our future energy needs. It is essential that new developments continue if stable coal prices are to be achieved and maintained. The challenge of the mining industry is to continue these developments in the face of problems related to increasing labor costs, inflation and environmental restoration. With expectations of increased activity in surface coal mining, the U.S. Bureau of Mines has authorized this study to determine the preliminary economic and technologic feasibility of underspoil haulage in area strip coal mines and to identify geologic and geographic areas where such a system could be used. These objectives were met by literature search, data-gathering visits to several active area strip mines and by analyzing various haulage systems that were superimposed on three model mines. Potential advantages of such a system include: 1) improved mine design; 2) lower mine operating costs; 3) improved land reclamation; 4) lower manpower requirements; 5) lower mobile equipment requirements; and 6) smaller, less sophisticated maintenance facilities.

Jan 1, 1975

By P J. B Fransen

Several spatially and/or temporally distinct phases of epithermal activity can be recognised in the Horohoro-Matahana Basin area of the Taupo Volcanic Zone. In the northern Matahana Basin a 140 - 350 ka age range is proposed for mineralised debris flow clasts and related (?) epithermal  mineralisation intersected in a recent drillhole. To the east, a ca. 40 - 50 ka age range is suggested for epithermal activity in the Waikaukau alteration zone which was focused along the Guthrie Fault. Hydrothermal explosion breccias occur over 13 km within the Guthrie Graben, and are probably sourced from vents in the south. Assuming a common origin, these breccias are constrained to a 45 - 50 ka age range. Within the Horohoro hydrothermal system (around the present hot spring), older (15 - 50 ka) and younger (0 - 15 ka) features can be distinguished.

Jan 1, 1991

By R. C. Courtney, D. J. Forrester

Modern advances have led to sweep and multibeam bathymetric surveying techniques that yield three-dimensional images of the sea floor and have also produced high-powered personal computers with which to control the data and analyse the results. At Sydney, in Nova Scotia, the topography of the sea floor over the longwall workings was observed before and after mining with a precision echo-sounder in 1987-89, with sweep bathymetry in 1993 and with multibeam bathymetry in 1994-95. The results of the latter programme produced what was probably the first observation of a complete three-dimensional subsidence trough over a longwall panel 2 500 m x 168 m. The subsidence has been quantified to a sufficient degree of accuracy to allow simple trend analysis, which has shown that the pattern and shape of movements are similar to those found elsewhere but with significantly smaller maximum subsidence. A prediction model has been calibrated

Jun 19, 1905

By Patrick J. Cain

The fatigue-failure characteristics under high-frequency (10 KHz) cyclic loading were determined for a marble, granite, and quartzite. The rock speci-mens were cyclicly loaded (using a high-power piezoelectric sonic transducer) at a constant strain amplitude generated by forming a longitudinal standing stress (strain) wave in the cylindrical test specimen. The number of load cycles required to fail each rock type at a given strain amplitude was deter-mined. The fatigue fractures were tensile in nature and the fracture load amplitudes were as low as 30 pct of the static tensile strength. Also the internal heating of the rock caused by the material damping (internal friction) was measured. The damping and internal heat generation in the specimens was analyzed to show that nearly all of the power input can be accounted for as a change in enthalpy in the specimen. Using these results the thermal strain in the rock was calculated to evaluate its contribution to fatigue failure. The thermal strain was found to range up to 30 pct of the dynamic strain amplitude depending on the load amplitude and the number of load cycles. The specific energy required for failure was determined and possible applications of the high-frequency fatigue fragmentation process are discussed.

Jan 1, 1975

The mining industry continues to be a major driver of the Australian economy generating over A$130 billion in export earnings in 2008/2009. However, the industry has been cited as a significant contributor to green house gas emissions. Australia's proposed carbon trading scheme, the Carbon Pollution Reduction Scheme (CPRS) will financially impact on mining operations; this calls for a holistic planning approach for mining operations taking into account the impact of the emissions trading scheme. Since carbon trading is a new area of study, particularly within Australia, the quantitative effect of the CPRS on the mining industry is uncertain and current mine planning practices do not directly consider emissions. This paper presents results of the study into the impact of the CPRS on a hypothetical large scale open pit operation, using a spreadsheet model based on linear programming and simulation. By varying the production rates, life of mine (LOM), carbon price and ore grades among other variables several scenarios were simulated to determine the impact of emissions trading scheme on the net present value of the project. This study found that the adoption of the proposed Carbon Pollution Reduction Scheme could impact mining operations in Australia by a three per cent to six per cent reduction in net present value, for carbon credit costs of $25/t to $50/t respectively. While the six per cent reduction in net present value for a mining operation is significant, rising fuel prices have had a similar effect in recent years. The most energy-intensive processes are the milling circuit and the flotation concentrator circuit. These processes are jointly responsible for up to 60 per cent of the total emissions, depending on the production rate and the level of offshore processing conducted. Clearly, the introduction of the CPRS makes it is imperative for mining companies to assess the impact of carbon emissions on a mining project during mine planning.

Dec 6, 2010

By Bruce E. Stauffer

The report recommends criteria for the design of safe surface mine haulage roads. Information relevant to road design at surface mine sites delineates vertical and horizontal alignment; subbase and surface materials; drainage; cross-slope, superelevation; runaway vehicle protection; and road and vehicle maintenance criteria. An appendix Is included which details the study methods used in compiling the final report information. A bibliography following the main text lists literature referenced for the report data and which is available as a valuable tool for use by individuals involved in haul road design.

Jan 1, 1976

By Herman D. Mendoza

A rapid recovery/recycling process was introduced utilizing the surface-chemical properties of finely dispersed mercury and alumina (Al2O3) fibers in aqueous environment. The conventional method of amalgamation or .ball milling. involves the mixing of a substantial amount of mercury to collect free gold during the grinding stage. In effect, a portion of the mercury is transformed into minute droplets that readily float and disperse in the amalgamation effluent. The fine droplets of mercury in the dispersion readily attached onto the positively charged macroscopic alumina fibers (i.e. = pH 9.8) at conditions pH 3 to 10. When an effluent from settling procedure after an amalgamation-grinding stage is passed through a column-bed packed with alumina fibers, maximum collection of negatively charged finely dispersed mercury occurred at pH 3 to 6. The collection/attachment efficiency was 99.5%. The collected droplets of mercury, which are left in the column-bed of alumina fibers, were subsequently rinsed with alkaline solution at pH 10 to 11.5. At these conditions, both mercury and alumina fibers carry negative surface potentials and resulted in the partial detachment of mercury from the alumina fibers. The detachment efficiency was only 30-35%. The attachment/detachment mechanisms in this study were analyzed using the DLVO theory.

Jan 1, 2003

By B. E. Eakin, A. L. Lee

Atmospheric pressure viscosity values For light hydrocarbons were calculated by a simple mixing rule based on the Sutherland constants for pure components. This method was further extended so that the atmospheric pressure viscosity of a mixture may be calculated based on the molecular weight information only. INTRODUCTION A proven method for estimating the gas-phase viscosity of a mixture is the one by Herning and zipperer.l This mixing rule has the following form: One method for calculating the pure component viscosity i is the Sutherland equation,2 which has the following form: The Sutherland constants B and S are determined from experimental data. A set of Sutherland constants for light hydrocarbons based on the data of several investigators3-5 is presented in Table 1. APPLICATION The Herning-Zipperer equation and the Sutherland equation were used to obtain an equation for calculating the gas-phase viscosity of light hydrocarbons. This equation has the form, Eq. 3 was used successfully in the study of methane-n-butane mixtures.6 Further analysis indicated that the Sutherland constants are a function of molecular weight.7 The gas-phase viscosity may be calculated based on molecular weight information only. The following equation was developed: The atmospheric pressure viscosity of ethane, propane, n-butaneand four methane-propane mixtures calculated on the basis of Eq. 6 are compared with the data of other investigators in Tables 2, 3, 4 and 5, respectively. A plot of atmospheric pressure viscosity vs molecular weight based on Eq. 6 is presented in Fig. 1.

Jan 1, 1965

The following is a 'partial list of members and guests who called at Institute headquarters during the period Oct. 10, 1917, to Nov. 10, 1917. Edwin T. Blake, Berkeley, Cal. Alfred C. Lane, Tufts College, Mass. H. M. Boylston, Cambridge, Mass. W. G. Matteson, Houston, Texas. W. B. Cogswell, Syracuse, N. Y. E. Francis M'Crossin, Birmingham, Ala. Paul R. Cook, Zaruma, Ecuador. R. E. Murray, Butte, Mont. F. W. DeWolf, Washington, D. C. Edmund Newton, Minneapolis, Minn. A. Faison Dixon, Venezuela. J. J. Ormsbee, El Paso, Texas. W. H. Dufur,, Oil City, Pa. Pablo Ortega, Havana, Cuba. Maxwell E. Erdofy, Lieut. Engr. Officers'. W. E. Pomeroy, El Paso, Texas Reserve Corps, New York. J. C. Ralston, Spokane, Wash. Evan Fraser-Campbell, Scotland. W. L. Remick, Chrome, N. J. David B. Gemmill, Crown King, Ariz. Howard D. Smith, San Francisco, Cal. F. Lynwood Garrison, Philadelphia, Pa. Harold C. E. Spence, Steeple Rock, N. M. C. J. Hall, Spassky, Siberia. R. K. Stockwell, Salt Lake City, Utah. H. Hamada, Tokyo, Japan. Maurice W. Summerhayes, Timmins, Rush M. Hess, Bouse, Ariz. Ont., Canada. A. Howard Higgin, London, England Malcolm M. Thompson, Morsemere; N. J. A. O. Ihlseng, Joplin, Mo. Nicholas Truschkoff, Petrograd, Russia. T. Ishikawa, Japan. H. J. Wendler, Los Angeles, Cal. C. H. James, Tucson, Ariz. Ira T. Wright, Hurley, N. M. R. R. Landon, Philippine Islands. C. Yabe, Japan. Robert W. Bissell has now become associated with Gunn, Richards & Co., of New York, N. Y. Major Reginald W. Brock is giving a course in a school for commanding officers in England.

Jan 12, 1917

By Darrell Wilder

When designing excavation support systems in urban environments, it is often necessary to consider the effect of vertical surcharge loads from adjacent structures. Several methods are used in practice to establish the horizontal surcharge-induce pressure on the excavation support. According to the experience of the authors, these methods often seem to overestimate the effect of the surcharge and may have significant impact on the construction costs. This paper explores several of these procedures and provides a discussion as to the reasons for the differences in surcharge effect predictions between different procedures. It also provides practical recommendations for designers dealing with excavation support design.

Jan 1, 2006