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By O Salisbury

Ingress of air into the longwall goaf environment needs to be managed appropriately to reduce the risk of creating a spontaneous combustion event. The maingate goaf edge is an area of particular concern in this respect, as air often penetrates for some distance into the goaf along this region inbye of the longwall face. Since the flow rate in this part of the goaf is also quite low, an opportunity exists to disrupt the air pathway by implementing a barrier to the airflow. Previous attempts using plugs made from an assortment of materials have resulted in varying degrees of success. More recently, Narrabri Coal Operations (NCO) has introduced the use of a chemical foam that is mixed with nitrogen to produce a standing barrier with the consistency of shaving cream. The implementation of this practice has consistently proven to be very effective for reducing the oxygen concentration along the maingate goaf edge by systematically retreating the foaming unit with the longwall. This paper presents how the foam is applied in the underground goaf environment to prevent oxygen ingress and uses results from gas monitoring to confirm the foam effectiveness.

Oct 12, 2022

By F. F. Peng

For a given flotation system, the rate-controlling step in fine coal flotation can be the attachment of bubble to the fine coal particles. The probability of attachment depends upon the surface characteristics and the collector adsorption on the coal particle surfaces. Thus, to further improve the flotation rate and selectivity is to alter the distribution of hydrophobicity on coal particles efficiently by applying the effective means of collector dispersion. In order to enhance the combustible recovery and selectivity of fine coal flotation, and lower the amount of collector used in the fine coal flotation processes, four modes collector dispersion/addition techniques are tested. They are direct liquid addition in pulp (mechanical agitation), ultrasonic energy dispersed collector into pulp, atomized collector into pulp and gasified collector transported by air and formation of collector-air bubbles in pulp. The effect of four collector dispersion/addition methods on the floatability of -600 µ m (-30 mesh US sieve) coal samples from four ranks of coals were studied. The ultrasonic energy dispersed collector and atomized collector flotation processes enhance flotation yield and most significantly improve the kinetics of fine coal flotation. The gasified flotation process can increase the selectivity of separation and decrease the collector consumption due to starvation flotation is achieved in this process. The flotation efficiency of gasified collector process is as high as that of conventional flotation. It is because that the effect of the decrease in the combustible recovery is offset by the increase of selectivity. In addition to flotation experiments, induction times of bubble attachment to the bed of fine coal particles for four ranks of coals are measured.

Jan 1, 1992

By Y. M. Jiang

Many underground instabilities, such as excessive shield loading and roof falls, occur at longwall faces causing safety problems and production losses. Such instability problems are directly related to roof conditions which can be categorized using geological information. . However, most geologic information describing anomalies and variations of immediate and main roofs are not available before mining resulting in unexpected problems in a longwall face. It is apparent that the evaluation of these geologic anomalies provides a great benefit for longwall stability. The purpose of this study is to evaluate roof categories associated with geological anomalies employing fuzzy set theory. The evaluation is based on real-time monitoring information, such as shield leg pressure, developing load on shields, intervals of periodic weighting, and the ratio of developing loads during periodic to normal times. This paper introduces the application of fuzzy set theory for characterizing roof conditions and evaluating of roof similarities.

Jan 1, 1995

By Bure R

Approximately 2.4 million ounces of gold and 11.3 million ounces of silver have been produced from the Umuna Lode by Misima Mines Pty Limited between June 1989 and the end of Decemeber 1996. Reserves remaining at the end of December were 32.1 million tonnes at 1.0 gram per tonne gold and 9.7 grams per tonne silver. To attain precious metal production of this volume, an estimated K60,000,000 (1996 Kina) was spent on exploration alone. from the 1940s to the present day. Exploration expenditure for the 1996 calendar year was approximately K4,400,000. With such a large investment in exploration, large quantities of data were generated and stored in various forms. To make best use of this data, it was necessary to organise and systematically store this data in a form compatible with a modern Geographical Information System (GIS). The Umuna Lode on Misima Island is a low sulphidation gold- silver deposit dated at 3.5 ¦ 0.2 Ma. The deposit is controlled by the 50 to 100 metre wide Umuna Fault- a moderate dipping, brecciated clay- chlorite- carbonate altered, normal fault zone. There is approximately 230 metres of mostly dip slip offset on this fault, which is measurable by the offset of the Cretaceous schist, marble and greenstone host sequence. Late Miocene microdiorite spatially related to the Umuna Lode does not appear to be genetically related to the gold- silver mineralisation. GIS was introduced to Misima at the end of 1995 and until recently has been mostly used for data storage and retrieval, the over- laying of various data sets to assist in targeting prospective areas, and as a drafting tool. The use of data-driven, predictive data analysis is the most recent effort in maximising the use of the extensive Misima database. By characterising the key controls and properties of the Umuna- type mineralisation, a Weights of Evidence, data-driven analysis produced a prospectivity map of Misima Island. The purpose of this map was to identify prospective areas yet to be explored and to assess the effectiveness of exploration to date.

Jan 1, 1997

By E. M. Schern

The Morenci/Metcalf porphyry copper mining operation, located in southeastern Arizona, currently processes approximately 100,000 tons of ore per day and has copper ore reserves estimated to be in excess of one billion tons. Functional groups within the Geology Depart¬ment (currently staffed with six professional and two support personnel) include mine geology, project geology, and hydrogeology. The primary task of mine geologists is daily preblast bench face mapping with grade and mill amenability estimates. Auxiliary duties include detailed in-pit metal distribution evaluation, mineragraphic work and flux quarry geology. Project geologists conduct explora¬tion and preliminary development projects both within and outside the Morenci district and provide support to ore reserve block modeling and geotechnical work performed by the Morenci mine engineering group. Hydrogeologists handle exploration for and development of groundwater' resources and groundwater flow modeling, mine dump leach solution penetration and recovery evaluation, and tailing dam water reclamation.

Jan 1, 1983

By John S. Owens

The National Steel Pellet Project and the Butler Taconite Project are operated by The Hanna Mining Company in the vicinity of the towns of Keewatin and Nashwauk, on the western Mesabi Range. Production began in 1967, after seven years of exploratory and development diamond drilling and reconnaissance magnetic surveys, Previously, direct shipping hematitegoethite ores and gravity concentrates had been produced in the area from numerous open pits and several underground mines since the start of the century. Total shipments of these oxidized ores amounted to more than 200 million tons, but at the present time such reserves are nearly exhausted, and there are no mining operations in the Keewatin-Nashwauk area except at the two taconite projects. The locations of all of the present taconite operations on the Mesabi Range are shown in Figure 1, extending for a distance of about seventy miles from the Butler plant to the Dunka River area. The Butler and National plants have a combined rated capacity of 4.4 million tons of pellets. Their reserves cover a combined strike length of about eight miles on the Biwabik iron formation. All of the intervals between present taconite operations on the Mesabi are potential sources of additional magnetic taconite; in particular, exploration and economic studies have been carried out by Jones and Laughlin Steel Corporation in the Biwabik area between Aurora and Virginia, and by Pickands Mather and Company in the Hibbing area. However, west of the Henna and Butler holdings, it appears unlikely that magnetic taconite exists in commerical quantities at economic depths due to extensive oxidation of magnetite to hematite.

Jan 1, 1968

By D. S. Choi

Coal is expected to become an increasingly important source of energy in the future. Coal production has already increased from about 650 million tons in 2975 to about 875 million tons in 1984 (Wilkinson, 1985). The declining trend of labor productivity in the early seventies was a source of concern for Consolidation Coal Company (Consol). To improve productivity, a gradual change from room-and-pillar mining to longwall mining has been taking place within Consol. Consol produces 45 million tons of coal annually with about 70 percent of the production coming from underground mines. Consol introduced longwall mining in the early seventies and currently operates about 20 longwall faces. The longwall faces are in mines in the Appalachian region in the States of West Virginia, Pennsylvania, and Ohio. The successful operation of longwall faces has contributed to a recovery of productivity and to an improvement of mine safety.

Jan 1, 1985

By C. Musingwini, C. Beaumont

"Kansanshi mine, located in northwestern Zambia, uses conventional openpit mining to produce primarily copper, with gold as a by-product. The ore is extracted from a deposit with highly complex mineralogical suites that are difficult to process, sometimes leading to poor recoveries. The mine was using an ore classification system called ‘Mat-Type’, which classified various ore types into 22 different quality categories, ranging from poor to good quality. Ore with poor recovery was classified as ’poor quality’ ore and directed to long-term stockpiles. Due to a lack of proper integration between the technical and functional areas forming the mine value chain, Mat-Type unintentionally misclassified ore. A geometallurgical analysis was therefore undertaken to review Mat-Type and a new geometallurgical ore classification system, called ‘OXMAT ’, was developed to replace Mat- Type.When implemented, OXMAT eliminated nine of the 22 ore categories and the remaining 13 ore categories could now be more accurately and consistently defined, leading to a significant change in the quantity of ore being mined. OXMAT demonstrated that within a defined test volume of the geological model, waste tonnes could be reduced by 19% while ore tonnes could be increased by 17%. This paper therefore demonstrates the value created through integrated geometallurgical modelling. IntroductionKansanshi mine is located in northwestern Zambia, approximately 10 km north of the provincial capital Solwezi and about 160 km west of Nchanga mine in the Central African Copperbelt (Broughton and Hitzman, 2002). The location of Kansanshi mine relative to other major copper deposits in the Copperbelt is indicated in Figure 1.Kansanshi mine uses conventional openpit mining methods to exploit copper- and gold-bearing veins hosted in a structurallycontrolled mineral deposit. Mining is carried out in two areas of the deposit, the Northwest and Main pits. A third area of the deposit, called Southeast Dome, is currently not being exploited (Figure 2)."

Mar 1, 2019

By Clara Godoy, Álvaro Dapía, Paulo Couceiro, Pablo Segarra, José Ángel Sanchidrián, Juan Navarro

This paper applies geostatistical tools in Measure While Drilling (MWD) data to estimate the probability distribution of values in all the points of the studied domain in order to assess the continuity of rock classes between boreholes. The analyses carried out by Ghosh et al. (2018) and Navarro et al. (2019) have been used as starting point of this work to classify the geotechnical rock condition in four classes: solid rock, fractured rock, cave- in rock and cavity. From it, an application for the geotechnical rock condition of orebodies have been developed, aiming at characterizing the rock before the charging the holes to minimize unexpected rock conditions and to address issues associated with charging and blasting operations. Such problems are closely related with non-optimal rock fragmentation after blasting.

Feb 1, 2020

By Y. C. Kim

This paper reviews the past 18 months of geostatistical work in a coal deposit performed jointly by the University of Arizona and the Homer City Owners. The objective of the study was to better predict the in-seam sulfur values of the deposit for the purpose of future emission control. Based on initially available 112 DDH information, variogram models were developed for Sulfur, Ash and Thickness for the entire deposit. The deposit was then kriged using 333 m x 333 m (1000 ft x 1000 ft) panel size. The estimation variance information obtainable from geostatistics was next utilized to improve the development drilling activities that were underway. The results of this effort are presented in this paper. In addition, this paper describes (1) the reasons for preferring kriging over the conventional isopachs, (2) the results of empirical validation of the kriged estimates using 19 additional DDH information, and (3) up-to-date experience on the use of conditional simulation of the same deposit for the future emission control strategy development.

Jan 1, 1980

By Z. Kokesz

The following paper presents the results of geostatistical studies of the selected hard-coal deposits in Poland. Geostatistical methods were applied mainly to the characterization of variability structure of the coal seams thicknesses as well as sulphur and ash contents in the coals. Results imply that the accuracy of coal reserves estimations can be improved if kriging method is applied. Kriging allows predicting more precisely the values of such parameters as thickness and sulphuring content.

Jan 1, 1993

Geostatistical methods have become well established in the last two decades for the evaluation of ore reserves in base metal, industrial minerals, coal and gold deposits of the Witwatersrand type. However, there has been considerable debate about the applicability of geostatistical techniques when applied to vein-type gold deposits with hydro or epithermal mineralisation. The main problems stem from a lack of spatial continuity and the highly erratic sample values that characterise these deposits. This paper reviews some of the current geostatistical techniques that are applied to the evaluation of gold prospects.

Jan 1, 1992

By W. Soetaert, P. Dhar, H. R. Kota, M. Thornhill, S. Roelants, I. V. Chernyshova

Yeast-derived bola-amphiphiles have attracted considerable attention for their applications in various industrial sectors in recent years. However, only a few studies on this class of surfactant were reported to be relevant to mineral processing applications. In this paper, one of the novel surfactants, acidic glucolipid obtained from Candida bombicola sophorolipids and modified by using Penicillium decumbens naringinase substrate has been evaluated for its interaction with chalcocite and calcite minerals because of a new Cu-ore Nussir deposit in Norway containing calcite impurity. The interaction of glucolipid biosurfactant with copper sulphide and carbonate minerals was investigated with zeta potential, adsorption and FTIR studies, and also by Hallimond tube and bench scale flotation tests using pure minerals and Nussir copper ore, respectively. The results illustrate collector adsorption and flotation of copper sulfides at neutral pH. The bench-scale flotation results demonstrate that copper sulphides can be selectively floated from carbonate and silicate gangue minerals. This study underlines the glycolipid’s high potential for its use as collector for flotation of valuable copper sulphide minerals. Keywords: Flotation, biosurfactants, adsorption

Jan 1, 2020

By F. P. Hassani, A. Hara, M. Momayez

To be competitive on the international market, the Canadian mining industry must reduce its costs, increase its productivity and maintain a high standard of safety. There is a great need today for improved methods that would allow the detection of geological structures in advance of mining to reduce dilution and the monitoring of underground structures to increase safety. This will facilitate planning for optimum exploitation of the mine and to increase production at lower costs. This paper discusses two examples of more efficient mine planning using new technologies such as Ground Probing Radar (GPR). In Kidd Creek mine, GPR technology was used at the 2500and 2600 levels to (1) monitor the stability of the sill pillar; (2) locate the presence of disseminated sulphide pockets in the sill pillar for extracting the mineral content; (3) monitor the stope backs and wall structures to evaluate the effect of on-time filling sequences; and (4)assess rockfill quality in terms of the presence of voids and fractures within the rockfilled areas. In the New Brunswick coal mine in Minto, GPR was used along with core log data to map and construct a 3D block of a section of the bench showing the relative position of different layers overlying the coal seam.

Jan 1, 1996

By Phil W. Welch

At first glance, the similarity between the fine grinding of cement clinker and coarse grinding done in other mineral processing industries may seem remote. However, it is interesting to note that the mill discharge fineness of cement clinker is only 70 to 90% passing 100 mesh and quite comparable to other mineral processing grinds. There is however, a greater dependence of the mill on the air separator in the finish grinding of cement clinker than in other mineral processing industries which explains why a technique to guage the balance between a mill and separator first began in the cement industry. (1) More recently an adaptation of this technique has shown its application to the processing of phosphate rock and is the central topic of this paper. First, an explanation of work done with fine grinding cement circuits seems appropriate together with a few general comments regarding cement. When unground or partially ground cement clinker enters a finish grinding mill, it is subjected to mechanical forces of impact and attrition which gradually reduce it to a range of sizes characteristic of finish cement. That is, a range of approximately 1 to 125 microns. The large proportion of superfine particles relative to the coarse and intermediate size particles is typical of portland cement particle size distribution. It accounts for the workability characteristics of plastic concrete and the early strength development of concrete which is so necessary to its successful use as a construction material. For this reason It is quite evident from quality control tests when a shortage of superfines exists.

Jan 1, 1975

By Helmut Hass, Michael S. Shultz

For many tunneling, deep shaft and deep excavation projects ground freezing is one of the best if not the only technique available to create a watertight and load bearing temporary support system in soft ground conditions. When appropriate attention is given to the details of the ground freezing system design, ground freezing is a very safe method and is economically viable with competing techniques and combinations of techniques. Recent innovative uses of the technique in Europe are highlighted in this paper and compared with current uses in North America.

Jan 1, 2005

By V O’Brien

The suitability of magnetic surveys flown at low altitudes to identify buried heavy mineral (HM) strands has long been accepted. This is despite the low intensity magnetic response often obtained from such strands. The fundamentals of the magnetic survey method dictate that the closer the instrument is to the source the stronger the response. As such the optimal elevation for the magnetometer is at or near the surface. Iluka sought to use a ground based magnetometer to aid in the exploration target generation process and allow accurate targeting of exploration drill holes. Following the initial trial Iluka recognised the potential additional application of data obtained by a ground based magnetometer over known strand deposits. The detail of the ground magnetic images can confirm the assumed strand continuity between cross-sections of close spaced drilling and can aid in the definition of the geometry of different generations of mineralisation. The ability to confidently determine that the deposit has not been truncated by post emplacement erosion of the mineralised deposit may enable reductions in drilling requirements as well as assisting mine planning activities. Iluka intends to investigate advanced modelling of the magnetic data to determine the level of strand geometry and HM content resolution that can be achieved from the ground magnetic survey data and its potential application in the mining grade control process.It is anticipated that the surveying of Iluka’s known resource deposits will provide the ability to correlate the magnetic response from new exploration targets with those from known deposits for a given depth, HM grade and mineralogy suite.

Oct 5, 2011

By J Karlovšek

Civil engineering infrastructures are often subjected to different types of natural and mechanical activities. These influences may result in serviceability or even in stability of structures due to material deformations, increased water content within the materials used or the formation of internal or adjacent cavities that may threaten the infrastructure. Construction practices can lead to development of such defects in the form of cavities. In civil engineering it is crucial to detect these variations in material properties and to detect the presence of defects. However, as they are often hidden from view, these attributes may be difficult or impossible to target with traditional testing methods. For these reasons rapid geophysical methods, such as ground penetrating radar (GPR), are increasingly being used. At the University of Queensland (UQ) GPR is used for detection of voids and cavities which have been caused by an over excavation of the earth pressure balance machine (EPB) operating in a closed mode.A variety of numerical simulations using the finite-difference time-domain (FDTD) methods and preliminary experiments have been carried out in order to specify information about the nature, type, size, location and other characteristics of targets to be detected by GPR. In doing this the difficulty of interpreting GPR data, which is mainly due to the complexity of the factors involved in multiple possible solutions of the observed features, can be overcome.

Mar 8, 2011

By K Ramachandra Rao

This paper explains the methodology for assessing the efficiency of rockmass fragmentation by explosive blasting, from ground vibration frequency spectrum analysis of the blast event. Explosives are used in the mining, quarrying and construction industries for fragmenting rockmass to a suitable size. When an explosive charge is detonated, in addition to fragmenting the rockmass, it will also generate ground vibration and air vibrations. Efficiency of a blast depend upon percentage of blast energy wasted in generating ground vibrations and air vibrations.

Jan 1, 1994

By Steve L. Bessinger, Luis B. Giraldo, Joram Shenhar, James D. Pile

This paper discusses the Helical Drag Bit (HDB) and its rock drilling applications with an emphasis on use in mining operations. The HDB is a drilling tool that employs cutting members arranged in a pattern to form a helical groove or thread within a borehole. This pattern of cutters can be used for several purposes including roof bolting in mining, interpretation of the lithology of the strata being drilled and low energy consumption drilling. Laboratory and field experiments have consistently shown increase of roof bolt-anchoring capacities in weak rock of more than 100% using the short encapsulation pull test method when boreholes are conditioned using the HDB. In 2004 a series of tests conducted in mines with weak roofs demonstrated the benefits of HDB technology for roof bolting applications in mining. HDB technology offers opportunities for new and beneficial approaches to interpret the geology of roof strata. During conventional drilling, traditional approaches to determine rock properties require simultaneous measurement of several parameters such as thrust, rotational velocity, torque and penetration rate. The unique geometry of the HDB possesses a characteristic that allows determination of the mechanical properties of the rock being drilled by measuring torque as a single drilling parameter. This capability greatly simplifies the process of determining rock properties and provides reliable results. Additionally, HDB technology has been demonstrated to offer significant advantages for rock drilling. A substantial portion of the rock is removed by the fracturing of the internal thread created in the rock bore by the tool taking advantage of the weakness of the rock in tension. Because the rock chips obtained in this process are relatively large, savings in energy are realized when compared to traditional drilling technologies.

Jan 1, 2005