Search Documents

By Duane L. Whiting

The National Environmental Policy Act of 1969 (NAPA) provides guidance for federal agencies in making informed decisions. The Act has been used to determine the potential environmental impacts from mining and other natural resource operations, primarily in the Western USA. To accomplish the purpose of the Act, a process for developing environmental documents was established. The documents (EA/EISs) evaluate environmental impacts and are produced by federal agencies through public participation and cooperating agency review. Effective interactions and up front coordination between agencies and industry is required. An abbreviated history of environmental protection in the USA leading to NEPA, the driving regulation, objectives, provisions and limitations of the Act, and select mining related NEPA projects III the Western U.S. are discussed in this paper.

Jan 1, 1998

The purpose of this paper is to present the methods used in ground water control and the considerations that affected the development of these techniques. Production at Knob Lake is currently proceeding at depths which may be as much as 200 feet below the original standing water table. In order to produce a more saleable product and to improve operating and maintenance conditions, it is necessary to depress the water table below the mining level. Considerable success has been achieved by drilling deep wells in strategic locations and installing vertical tur-bine pumps at depths of up to 400 feet. This method is especially suitable for operation under severe winter conditions and has reduced the detrimental effects by a far greater extent than other methods of water control, Spring runoff is handled in open sumps, but all other water from four mines, with flows exceeding 16,000 g.p.m., is pumped all year 'round from about thirty-five wells. T HE Knob Lake operation of the. Iron Ore Company of Canada is located on the Quebec-Labrador border, 320 miles north of Sept Iles,

Jan 1, 1965

By T Ireland, S Eratne, W Newns, P Spies

The approach to risk management during the procurement of major projects often has a significant outcome on the ultimate delivery of a project. The NZ$1.4 B Waterview Connection project is the largest and most complex project yet undertaken by the New Zealand Transport Agency (NZTA) and the procurement process for an alliance contract was refined to provide compliance with the International Tunnel Insurance Group (ITIG) Code of Practice for Risk Management of Tunnel Works (TCoP). The principle of shared risk within an alliance incentivises a common understanding of project risks prior to finalising the alliance agreement and therefore enables superior risk management through design, construction and beyond. Risk management practices need to be instigated well in advance of commercial phases, so that commercial competition does not lead to a significant elevation of project risk. In particular the practice of gaining commercial advantage by taking on a potentially unmanageable level of risk is one of the outcomes to be avoided by the TCoP.During the procurement phase the NZTA placed high value on design and construction mitigation measures proposed in order to address ground risks, as is appropriate for a major tunnel project. In order to achieve alignment on the level of geotechnical risks an Alliance Geotechnical Baseline Report (AGBR) process was developed.This paper describes the measures taken during the procurement process to achieve certainty with respect to outcomes and minimise project risks whilst also achieving value for money. Refinements to the procurement process to ensure compliance with the TCoP prepared by the International Tunnel Insurance Group (ITIG) are described along with the AGBR process applied as part of a suite of measures to achieve a successful procurement outcome.CITATION:Ireland, T, Spies, P, Eratne, S and Newns, W, 2014. Risk management and use of a geotechnical baseline report for a competitive alliance procurement?process, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 553–562 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By D. C. Sharpstone

THE Polaris-Taku mine is a new gold property, situated in the far north-west corner of British Columbia. Production was started in November, 1937, at the rate of 150 tons a day, and recently has been increased to 200 tons. The property, which promises to become one of British Columbia's important gold mines, was developed and brought into production in twenty-nine months after work was started on it as a virtual prospect in June, 1935, by Edward C. Congdon and associates. Inaccessibility, extraordinarily complicated geological problems, and difficult metallurgy retarded development of the property before acquisition by the present interests, an::l, in fact, discouraged two companies that had spent substantial sums upon it from continuing development. This paper is concerned with reviewing the development of the property and describing the principal features of the geology, the mining and metallurgical practices, and the equipment employed. Acknowledgments The writer is indebted to Mr. Edward C. Congdon, President of the Polaris-Taku Mining Company, and to various members of the mine staff for their assistance in assembling the data for this paper. Special thanks are due to Mr. George G. Griswold, Jr., of Butte, Montana, who generously and painstakingly prepared the section dealing with milling and power. Microscopic studies of ores were made by Professors Frank Grout an::l G. M. Schwartz, of the University of Minnesota, and by Mr. Griswold.

Jan 1, 1938

By William C. Miller

This report describes investigations by the Bureau of Mines designed to establish the noise level and spectrum of various types of pneumatic rock drills and to furnish information that would be useful in conducting sound measurements in mining environments and in reducing the noise generated in pneumatic drilling. These investigations show that (1) the noise generated by the drills in the frequencies below 100 cps is caused by the impact of the piston and drill steel, in the frequency range between 100 and 2,000 cps by the exhausting of air from the ports, and in the frequencies above 2,000 cps by the resonant frequencies of steel drill parts and of drill steel; (2) satisfactory instruments and instrumentation systems are available for field and laboratory measurements; (3) reliable sound measurements can be made in mining environments; and (4) devices can be developed that will abate the noise.

Jan 1, 1963

By John A. L. Campbell

Although there has been an increased interest in the electrokinetic properties of coal (1) research on the subject is still in an early stage of development (2,3,4,5,6,7) To the author's knowledge, no electrokinetic studies have been made on coal lithotypes - particularly anthracite lithotypes. This paper presents the results of an investigation of the double layer properties displayed at the anthracite/water interface (whole coal and lithotypes) as determined by streaming potential methods, It is hoped that this investigation and related future investigations will provide correlations from which the surface properties of any coal can be predicted and then related to surface dependent processes such as froth flotation and flocculation. Another aspect of this research, undertaken to determine the physical and chemical parameters necessary for anthracite lithotype differentiation, was previously published (8). The number of parameters involved, lithologic, organic and inorganic, and the wide divergence of these parameters within an individual coal limits the practical utilization of the results, however, the results are of value and of interest in guiding theoretical developments. Keeping the limitations in mind, the results are analyzed in terms of their application to froth flotation processes and are used to indicate the feasibility of making a lithotype separation by flotation.

Jan 1, 1969

1. The following recommendations should apply to all mines, tunnels and underground quarries, but to opencast quarries only in so far as persons can be exposed to dust injurious to health. General In the present state of knowledge, all duets liberated in mining, tunneling and quarrying operations should be considered potentially injurious to health if breathed in sufficient quantity; dusts containing free silica should be considered specially injurious to health, the injurious particles being below 7 microns in diameter.

Jan 1, 1954

By M W. N Buxton, M S. Shishvan, J Benndorf

The flow of information, and consequently the decision-making along the chain of mining from exploration to beneficiation, typically occurs in a discontinuous fashion over long timespans. In addition, due to the uncertain nature of the knowledge about deposits and the inherent spatial distribution of material characteristics, actual production performance in terms of produced ore grades and quantity and extraction process efficiency often deviate from expectations. Reconciliation exercises to adjust mineral reserve models and planning assumptions are performed with timely lags of weeks, months or even years.With the development of modern information and communication technology over the last decade, a flood of data about different aspects of the production process is available in a real-time manner. For example, sensor technology enables online characterisation of geochemical, mineralogical and physical material characteristics on conveyor belts or at working faces. The ability to utilise this additional information and feed it back into reserve block models and planning assumptions opens up new opportunities to continuously control the decisions made in production planning to increase resource recovery and process efficiency. This leads to a change in paradigm from a discontinuous method to near real-time reserve reconciliation and model updating, which calls for suitable modelling and optimisation methodologies to quantify prior knowledge in the reserve model, process and integrate information from different sensor sources, back propagate the gain in information into reserve models and efficiently optimise operational decisions in real-time.This paper introduces the concept of an integrated closed-loop framework for real-time reserve management, incorporating sensor-based material characterisation, geostatistical modelling under uncertainty, modern data assimilation methods for sequential model updating and mining system simulation and optimisation. The effectiveness of the framework and the value added will be demonstrated in an illustrative case study.CITATION:Benndorf, J, Buxton, M W N and Shishvan, M S, 2014. Sensor-based real-time resource model reconciliation for improved mine production control – a conceptual framework, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 223–234 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By Patrick Browne

Drilling programs and the study of active geothermal systems have shown that the reservoir rocks in many fields contain minor quantities of base and precious metals. Commonly, base-metal sulfides occur in the subsurface but, where present, Au, Ag, Hg, As, T1 and Sb rich precipitates deposit near, or at, the surface. Although in some fields (Geysers, Larderello, Tongonan) some of the ore minerals (and others) are relict, there is evidence that they are now depositing in a few systems. Recent work on active hydrothermal systems in New Zealand shows that: (1) Sphalerite, galena, chalcopyrite (forming veins and disseminated discrete crystals) plus rare pentlandite, cobaltite and arsenopyrite, occur at Broadlands, NZ. Rare quantities of base-metal sulfides also occur in cores and cuttings from the geothermal fields of Waiotapu, Kawerau, Tauhara, and Ngawha. Further, Kakimoto (1983) has identified cassiterite, native silver, and trace gold in cores from Tauhara, in the south-eastern part of the Wairakei field. Bore temperatures at the depths from which these minerals were recovered are mostly between 220° and 300°C, but at Broadlands are locally as low as 120°C. The host rocks are Quaternary talc-alkali, silicic lavas and pyroclastic rocks, andesites, dacite and deep Mesozoic greywackes and argillites; however, there is no obvious relationship between mineralization and stratigraphy, permeability or well output. (2) The deposition of amorphous precious metal precipitates (Au, Ag, Hg, As, Sb, T1) from hot springs and well discharges has taken place at Broadlands, Waiotapu and Rotokawa; it also occurs at Kawerau. (3) Water discharging from Frying Pan Lake, Waimangu, is presently depositing siliceous sinter containing up to 4.1% tungsten. A characteristic of mineral-depositing fluids in the New Zealand geothermal fields is their very low salinity (total dissolved salts of 3000 ppm or less but with high CO2); they are of near- neutral alkali chloride composition, although water discharging from Frying Pan Lake has a pH of 4.5, and very low metal contents. Very effective concentration processes (10 times for gold at Broadlands) must occur: in the subsurface these include boiling and rapid cooling but near, and at, the surface, mixing of waters of different pH seems to dominate. In particular, descending acid condensate, derived from separated steam and oxidation of H2S mixes with its parent alkali chloride water, resulting in precipitation of amorphous ore metals. Base-metal sulfides also occur in veins and as disseminated grains in geothermal fields at Tongonan, Leyte and Southern Negros, Philippines. These fields have a porphyry-type setting with host rocks of Miocene andesitic lavas and pyroclastics intruded by diorites so that the fields have undergone complicated thermal histories before cooling to their present base temperatures of about 325°C. Precious metals have precipitated from waters from some wells (Leach, pers. comm.) but they do not, as yet, form ore-grade deposits.

Jan 1, 1984

By B L. Dickson, E, M F. Lee, P A. Mikula

Computational techniques are needed to assist in the analysis and interpretation of the increasing amounts of geoscientific and mining related data and information that are routinely gathered at mine sites. New interpretation methods are needed to provide an integrated approach so as to establish relationships (cause and effect) or to be predictive about possible outcomes based on acquired data. Traditional multivariate statistical methods are often confused by variable relationships that are non-linear, data distributions that are non-normal, and by the data themselves that may contain missing values, text and both continuous and discontinuous numeric values. Modern data mining methods are available to understand the relationships within and between diverse data sets, and identify relationships or trends associated with processes, measurements and mine design parameters in mines. The self-organizing map (SOM) is a data mining approach with the advantage that all input data samples are represented as vectors in a data-space defined by the observations (variables). The SOM procedure is an exploratory analysis tool that highlights patterns and relationships. Results are internally derived, in an unsupervised fashion based on measures of vector similarity. Our SOM outputs are highly visual, which assists in understanding and illustrating the dataÆs structure and internal relationships. Two studies are presented. The first uses SOM to investigate the relationships between a range of measured and derived rock property parameters and their observed behaviours during mining. Our aim was to determine whether a SOM analysis would allow a better understanding of observed and predicted rock behaviours from their rock properties. The SOM analysis showed that there were indeed relationships between æbrittleÆ, æsugaryÆ, æslabbyÆ and æsqueezingÆ rock behaviours and a number of the input parameters. The computed SOM æstructureÆ was then used to assess the likely behaviour of unknown samples by assigning them into behavioural fields based on their measured and derived geotechnical responses. The second study was aimed at assessing whether a SOM analysis of microseismic data at the Kalgoorlie Consolidated Gold MineÆs (KCGM) Mt Charlotte mine can contribute towards understanding and potentially forecasting/minimising seismicity at the mine-design stage. The database comprised 40 sample æclustersÆ of microseismic parameters from the MS-RAP software package, which were derived from 2500 individual seismic events. The SOM analysis showed that some of the initial mining conditions are related to the seismic parameters. In each of the studies, the SOM procedures assisted in understanding the data and provided new insights. Because of its æordered vector quantisationÆ foundation, the SOM procedure is a substantial improvement over traditional statistical methods in three main areas:its ability to analyse data from disparate sources, including different data types; its ability to analyse sparse data sets with missing values; and its ability to analyse and visualise non-linear relationships within a data set.

Jan 1, 2006

By M S. Powell

In this paper it is argued that we are entering a new mining era, based on considerably more challenging orebodies as we rapidly expand minerals production by exploiting previously uneconomic deposits. Rapidly increasing production costs cannot be sustained by continually increasing commodity prices, as illustrated by the recent downturn in the industry.Driven by reduction in grade, requiring the processing of 50 to 100 per cent more ore to recover the same amount of metal, often accompanied by finer grain structure - necessitating a finer product size and more challenging recovery - the productivity of the mining industry is dropping in real terms. The author suggests that tweaking current technologies and relying on economies of scale will not turn the industry around, but rather a switch to considerably more efficient processing is required.It is imperative to utilise the properties of the orebody, especially in terms of variability, in revolutionising our processing techniques. Our new mantra may be æselective mass mining with flexible processingÆ. This paper explores how this may be implemented using current technology and equipment in order to change the cost profile of the new mining industry. Orebody knowledge, based on the underlying process drivers, rather than proxies, is required. These properties and their variability will need to be propagated into the orebody through utilising the geological data rather than smoothing block averages, which destroys information on variability.Novel flexible circuit designs are presented that can respond to a wide variability in ore properties and throughput requirements in order to slash processing costs and energy utilisation, while enhancing overall recovery. The success of these circuits will be based on an ability to predict at both design stage and in everyday processing the variable ore properties, which is dependent upon reliable orebody knowledge that caries variability and underlying processing properties.CITATION:Powell, M S, 2013. Utilising orebody knowledge to improve comminution circuit design and energy utilisation, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 27-36 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By Eli Robinsky

La disposición de relaves es importante en tanto busca proteger y rehabilitarlo el medio ambiente a un menor costo posible. En ese sentido, el presente texto describe el método de descarga densificada como el más adecuado puesto que logra una solución más aceptable desde la perspectiva ecológica. El método ofrece la ventaja de aumentar la capacidad de las zonas existentes para el almacenamiento de los relaves, sin requerir de la ampliación de las presas perimetrales.

Sep 1, 1983

By Michael R. Yenchek

The U.S. Bureau of Mines investigated the performance of portable power cables under transient conditions. This research had a twofold purpose: (1) to define the thermal characteristics of electrically overloaded trailing cables, and (2) to conceptualize electrical protection for cables that allows maximum cable efficiency without diminishing electrical safety in underground mines. Several tasks were undertaken in support of these goals during the 3-year research effort. Overload tests ranging from 2 to 12 times rated ampacity were conducted in the Bureau's Mine Electrical Laboratory. Two thermal models of energized type G-GC trailing cables were constructed, one based on thermodynamic theory and the other using empirical data from previous Bureau load tests. The empirical model was then incorporated into an interactive computer program that can assist designers and approvers of mining machines in selecting the appropriate size trailing cable. This program can be the basis for a cable protection system that ensures that cables are not the source of fires, ignitions, burns, or explosions underground.

Jan 1, 2010

By Raymond B. Ladoo

"The talc and soapstone deposits of Vermont have been worked more or less continuously for nearly 100 years, but all of the early efforts seem to have been directed toward the production of slabs for foot warmer, and other similar uses. Altho soapstone of good quality occurs at several places, much of the material first utilized was really talc and was not massive enough to be cut successfully. The grinding of talc in Vermont seems to have commenced in about 1902 and has shown continuous growth since that time. Statistics compiled by the Geological Survey in Mineral Resources of the ,United States show that the production of talc in Vermont has increased, from 8,978 short tons valued at $65,525 in 1905 to 93,960 short tons valued at $625,150 in 1917. Until 1917, New York was the leading producer in both tonnage and value with Vermont second, but in 1917, Vermont took the lead in tonnage produced, although not in value, with a production of over 47% of the total tonnage produced in the United States and over 35% of the world's pro-duction. This increase in production will probably be continued, though possibly at decreased rate, for the reserves of talc In Vermont are large.Active talc mines and mills in Vermont are found in four districts: Chester, Windsor County; Rochester, Windsor County; Waterbury, Washington County; and Johnson, Lamoille County, These mines and mills are distributed as shown in the following table:While there are a great many other known deposits of talc and soapstone in Vermont, some of which have been worked, those listed above are the only ones which have survived and are producing on a commercial basis. The closing down of many mines and quarries, for example, those at Perkinsville, Stockbridge, Reading, Cavendish, and Athens, has been attributed to several causes. Of these causes the most important seem to be exhaustion of the deposit, poor grade, long haul to the railroad, poor management due to lack of knowledge of mining methods and failure to consider talc mining strictly as a business proposition. The companies which are now operating with greatest apparent success are those which have realized the present and future possibilities of their industry, and have invested sufficient capital in both equipment and personnel to establish their companies on a firm business basis."

Sep 1, 1919

"This paper challenges the traditional notion that mine planners need to plan production so as to incur the lowest mining cost. For a given mine configuration, a mine that increases its mining rate will incur increased mining costs. In an environment in which operations are fixated on cost reduction, a proposal that increases costs will not be readily accepted. Such a proposal requires financial justification—the increase in costs might be recuperated by the additional production. This paper evaluates the net present value (NPV) across a range of copper prices for two underground orebodies located at different depths, using a production rate of 300 kt per quarter and a scenario that introduces additional equipment and costs for 450 kt per quarter. The evaluation was based on the changes of NPV for the orebody located at a shallow depth compared with the orebody at a greater depth. Discrete event simulation combined with mixed integer programming was used for analysis. Unlike traditional sensitivity analysis, this study re-optimizes the mine plan for each commodity price at each production rate. The results show that, for the low mining rate at the final copper price, an NPV of A$1530.64 million is achieved, whereas an NPV of A$1537.59 million is achieved at a higher mining rate. Even though pushing mining rates beyond traditional limits may increase mining costs, this option may be beneficial at certain commodity prices, particularly when prices are elevated. IntroductionA traditional notion among mine planners is that mining rates should be planned in such a way as to reduce production costs. This concept generally relates to the mining rate that results in the highest machine utilization for the selected equipment. Although an existing mine may consider increasing its mining rate by adding equipment to a given mine configuration, this typically increases mining costs. In an environment in which operations are fixated on cost reduction, a proposal to increase costs may be very difficult to argue for. The value of the mine plan is well recognized as varying with the mining rate for a given orebody (Smith, 1997)"

Jan 1, 2017

By L J. de Lange

As a material asset for mining entities, the resources and reserves (RR) estimation processes are surprisingly underrepresented in the assurance landscape. When press reports expose them being inaccurately reported, or in merger and acquisitions processes, their importance becomes clear. The impact of erroneous RR numbers (both positive and negative) could have a material impact on an entity’s reputation and value.The technical nature and ‘black magic’ connotations of the RR estimation processes are possibly reasons why audit committees are not actively involved with it. Internal auditors avoid the RR processes for similar reasons. Also the traditional approach to obtain assurance on RR is expensive and is therefore only performed when it is absolutely required.However, stakeholders’ expectations of good governance are growing. Part of this increased focus is based on attaining a higher degree of certainty about the current and forecasted position of the entity. Stakeholders are also increasingly more interested in non-financial areas of entities, as the future success of an entity is more than a set of financial metrics.Consequently, the RR estimation processes should be visible on the agendas of audit committees. Monitoring of key controls is required as part of the governance obligations for senior management and the audit committee. So once it is on the audit committee’s agenda, the question then becomes, how will that agenda be supported by an assurance process that is cost-effective?The main objective of the paper is to describe a model of RR assurance that has been effectively applied in some mining companies. The paper discusses one particular approach that provides an audit committee with the required assurance regarding RR processes. The approach ties the assurance needs of the audit committee to the needs of the technical experts in the entity, therefore involving two important figures. It also offers assurance providers with a model to audit ‘through’ the RR processes rather than ‘around’ them. The paper then discusses top-down and bottom-up approaches that provide assurance at different levels of an entity.A governance audit that focuses on the RR processes is suggested as a top-down approach. A bottom-up approach assesses the design adequacy of internal control processes. A hybrid model is described which meets the needs of diverse stakeholders including the audit committee and the RR community.The hybrid model combines the expertise of professionals in both internal audit and RR. The right balance of these skills directed by a singular approach ensures that a credible result is achieved.This approach is not as expensive as some verification approaches used in the industry and can, as a result, be performed on a more regular basis.The last element of the paper looks at implementation of the reporting mechanism. An assurance process aimed at continuous improvement further enhances the robustness and reliability of RR reported by an entity.CITATION:de Lange, L J, 2016. Resources and reserve assurance processes – a framework for improved governance, in Proceedings International Mine Management Conference, pp 21-34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By G. L. Oldright, Virgil Miller, F. K. Shelton, Keck. W. E., Horst Sieg

Potash is one of the principal foods and is necessary for the growth of most vegetables, grains, and fruits. For many years, this country depended entirely upon foreign sources for its supply of potassium compounds. However, during the last 15 years the domestic production of potash has gradually increased, as shown in table 1. 7/ Imports now supply only half of the American market. In 1936, the equivalent of 207,000 tons of K20 was imported, and 210,000 tons was produced domestically. In 1935, domestic consumption was approximately 420,000 tons of potash, a 57 percent increase over that for 1934 and surpassing previous peaks of 1928 and 1930.

Jun 1, 1937

By William Butler

El presente texto describe las oportunidades que tienen las naciones menos desarrolladas para un progreso en el campo de los recursos naturales. Para ello, se revisan los inconvenientes ocurridos en el manejo de recursos minerales tales como: los mercados mundiales tienen un sobreabastecimiento que son pocas las probabilidades de ingresos por exportación, la inestabilidad de los precios no permite basar la economía de la nación sobre su riqueza minera, la explotación de los recursos, reduce la riqueza de la nación, los beneficios que puedan obtenerse como resultado de una mayor eficiencia en la producción minera en los países menos desarrollados, se vuelca a favor de las zonas industriales. Por lo tanto, no hay mayor esperanza para aquellos países en propender a una mejor explotación de los minerales. En ese sentido, aquellas naciones que buscan un rápido desarrollo económico, deben buscar un manejo adecuado de sus recursos y así asegurar una fuente de ingresos en divisas extranjeras que les permitirá financiar las importaciones necesarias para su crecimiento y, a la vez, acrecentar sus conocimientos técnicos, como el bienestar de un sector importante de su población.

Jan 1, 1966

By Milford L. Skow

Utilization of domestic ores in the winning of metallurgical alumina requires a convenj.ent method of treating siliceous bauxites and other aluminous materials. In the United states there are only small reserves of high-grade bauxite but considerably larger tonnages of low-grade material. In addition, there are large deposits of high-alumina clays. If these high-silica bauxites or high-alumina clays could be beneficiated, either by are dressing or by chemical dissolution to remove a large proportion of the silica, then the potential reserves of aluminum ores would be increased materially. Faced with a similar situation, the German industry, chiefly dependent on high-grade French bauxites prior to World War II, was compelled during the war to Use lower-grade ores. For desilicating the lower-grade bauxites before the Bayer treatment, a method was developed in which the bauxite was calcined and then given a dilute caustic leach preliminary to the pressure digestion. It was planned to regenerate the caustic by treatment of the desilication liquor with lime. As European bauxites are mineralogically different from those found in this country, preliminary work was undertaken to determine whether this process might be applied to domestic materials. The results of this work, along with a review of the German process, are presented in this report.

Jan 1, 1950

By M J. Thurley, M Wimmer

To assess the present-day functionality of large-scale sublevel caving at LKAB Kiruna a comprehensive measurement program was undertaken involving blast function, fragmentation and gravity flow. As part of this assessment, a fragmentation measurement trial was performed based on 3D imaging of the drawpoint and corresponding bucket load of the underground load-haul-dump (LHD) excavator. 3D image data from stereo photogrammetry was collected and an automated image analysis strategy developed. A number of data sets were collected for each of the drawpoint and LHD bucket, along with sieving results for four of the LHD bucket loads (totally about 70 t). Two of the sieving results were used to inform the automated image analysis strategy, and two were held back as a comparison. Large variations in the visible particles are apparent when comparing corresponding drawpoints and LHD buckets highlighting the impact of sampling location and the need to measure large quantities of data in order to avoid bias from small samples. The results show that 3D imaging and analysis can produce fully automated measurement and analysis of the visible particle size distribution. Although this is not the same as the sieve-size distribution it provides useful estimation of both the larger size classes and a bulk estimate of fine material below approximately 60 mm. The 3D stereo photogrammetry measurement system used produced very high 3D point density but this was achieved using a custom up-sampling technique which significantly smoothed the data, removing small particles, smoothing edges, and this negatively affected the particle delineation algorithms.CITATION:Thurley, M J, Wimmer, M and Nordqvist, A, 2015. Blast fragmentation measurement based on three-dimensional imaging in sublevel caving drawpoints and underground excavator buckets at LKAB Kiruna, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 763–774 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015