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By Tom Denton

The bolt design criteria, since it was first published by Dr. John Stankus (Stankus, 1997), has been recognized as an important tool in ground control design. This concept is based on the Optimum Beam Building Effect (OBE), which is defined as the roof beam that has no separation above or within the bolted range and having the shortest bolt possible. This paper will present an application of this concept at the American Coal Company. Galatia mine. This mine previously used a 6' and 7' length bolt. However, since seam thickness has gotten smaller in the Southern area of the nine, a two-piece bolt is required. A two-piece bolt increases ground control costs and delays production. Therefore, a one-piece, shorter bolt, if feasible, can reduce costs and expedite development. In this analysis, Computer modeling is first conducted to determine bolt length and installed load. Second, a special bolt is developed, that can achieve the proper installed load as determined by the computer modeling. Third, underground bolt pull and load cell tests were conducted to evaluate bolt performance. Finally, an underground "bench" test was conducted. The test results have shown that entry convergence in the short bolt (5) test area is less than the 6' bolt area. Overall roof condition in the test area was as good as the 6' bolt area. Based on this analysis, the mine has converted to a shorter bolt in the low seam area and it is working well.

Jan 1, 2000

The borehole televiewer is a downhole geophysical logging device that produces continuous, oriented, 360¦ images of the drill hole wall. Two types of borehole images are currently being generated at the BHP Billiton Mount Whaleback deposit. The optical televiewer (OTV) tool captures a ærealÆ image of the borehole wall whereas an acoustic televiewer (ATV) generates an image through variations in physical borehole size, scattering the energy from an acoustic beam. Orientation of the resulting ævirtual coreÆ is derived through magnetometers and accelerometers, providing values within one degree for both inclination and azimuth. Downhole structures such as fractures, joints, foliations and bedding planes are selected directly off the borehole image, recorded and displayed in a 3D modelling package along side adjacent drill holes. Measurements are corrected from apparent to true dip and magnetic to true north. Strata-bound magnetic anomalies are identified and corresponding measurements excluded. The importance of borehole imaging increases substantially with its ability to integrate the OTV and/or ATV data with other forms of lithological and structural data. At Mount Whaleback, the borehole televiewer has been implemented to provide information for geotechnical exploration including structural analysis, lithological characterisation and rock-mass conditions. Within the large area in and around Mount Whaleback, drilling may intersect a number of different geological formations with various rock types and conditions. With the application of the borehole televiewer, reverse circulation drilling can provide information traditionally obtained by diamond drilling.

Jan 1, 2007

By X. Song, Q. Zhang

"The development of fracture zones in surrounding rock mass has significant impact on the stability of underground mine roadways. Detection of the fracture zones is of compelling importance for maintaining roadway stability as well as for safe and speedy excavation of the roadways. This paper presents a study conducted at Dong Bao Wei underground coal mine, where the roadways were developed in diabase rock mass. The roadways suffered severe damages, including sloughing and excessive floor heaving. The borehole imaging technique was applied in the study to observe and detect fracture zone development surrounding the roadway openings. Based on the borehole imaging studies, new roadway support systems were proposed to improve the stability. INTRODUCTION At the Dong Bao Wei Coal Mine three main roadways of the west wing were excavated. The three roadways had semicircle arch cross sections and were at a depth of 650 meters, each being about 750 meters in length. The roadways were driven through a section of thick diabase intrusion, which was softened by water with reduced strength and may turn into powder form under weathering. Site investigation indicated that the roadways in diabase intrusion zone were badly damaged due to severe deformation, and very serious roadway sidewall sloughing and spalling accompanied by severe floor heave often occurred.(Figures 1 and 2) In order to ensure the normal use of the roadway, undercuts were excavated. However, this operation seriously affected the roadway construction progress and increased the amount of roadway support operations as well as the roadway maintenance costs. Furthermore, a roof fall accident occurred in nearby drilling site. The investigation indicated insufficient support provided for the roadways which imposed significant safety hazards and would have serious impact to mining production and subsequent mining activities.The support of the main roadways is a critical task and is the focus of the underground opening excavation work at the mine, since more than 40 years of service life is required from these main roadways. For these roadways, large cross sections with high degree of stability and minimal amount of deformation should be maintained. Therefore, providing sufficient and appropriate roadway supports is of significant importance to the coal mine. In this paper, in order to optimize the roadway supporting system, studies were carried out on the geological structures, lithological characters, roof bolt anchoring features and suitable anchoring layers. The studies were aimed at ensuring the stability of mine roadways, reducing the roadway maintenance costs and providing a safe mine passageway for orderly production and progressive development of the mine"

Jan 1, 2016

By M. Tanaka, K. Aoki, T. Mori, H. Morioka, K. Iwano, T. Kanagawa

To estimate the detailed characteristics of the rock around the cavern during excavation, new monitoring technique for dynamic properties of the rock has been applied. In this paper, micro-seismic monitoring and AE monitoring technique are applied to the excavation of large underground rock cavern and the result was discussed to clarify the acutal behavior of EDZ around the cavern. Zur Einschätzung der Gesteinseigenschaften um die Ausschachtung herum haben die Autoren eine Technik eingesetzt, mit der die physikalischen und dynamischen Änderungen im Gestein um den Schacht während der Ausschachtung beobachtet werden. In der vorliegenden Studie wurde zur mikroseismischen Überwachung ein AE Überwachungsverfahren eingesetzt und die Autoren berichten über die Veränderungen in den Gesteinseigenschaften um die Ausschachtung herum. Dans le but d'évaluer en détail les propriétés des roches qui forment les parois des cavernes creusées, les auteurs ont utilisé une technique de mesure permettant d’observer les modifications physico-dynamiques des roches aux alentours de la caverne pendant son excavation. Dans le cadre de cet article, une technique de surveillance de l’agitation et du bruit microséismiques a été mise en œuvre et les auteurs font état de la modification des propriétés de la roche environnante.

Jan 1, 2003

By B. Yu, S. Kelebek, C. Gibson, M. Aghamirian

There are a number of high grade niobium deposits worldwide which have been deemed untreatable by flotation due to the very fine grained nature of the in situ pyrochlore, the primary niobium bearing mineral. A known method of recovering extremely fine particles is through the use of chelating reagents such as hydroxamic acids which have a strong affinity for transition metals. However, one of the major issues in the flotation of niobium bearing minerals using hydroxamic acids is the corresponding recovery of other transition metal gangue minerals including magnetite, hematite, and pyrite. In order to better understand the differences in behavior of niobium and iron bearing minerals in flotation with benzohydroxamic acid (BHA) and sodium hexametaphosphate (SHMP) at a range of pulp temperatures, a Box-Behnken experimental design was employed. Regression models for the global recovery of iron indicated that iron mineral recovery was significantly influenced by both BHA and SHMP dosage. Upon examinination of flotation products by semi-quantitative XRD, it was observed that recovery of iron oxide and sulphide minerals (hematite, magnetite, goethite, and pyrite) was problematic at high benzohydroxamic acid dosage, while sodium hexametaphosphate was mainly helpful for carbonate mineral depression. Iron rich carbonates (likely an iron rich dolomite) largely reported to the tails with increased SHMP dosage.

Jan 1, 2015

By Zhou Lu-Jian

The Port of Shekou is situated at Shenzhen Bay on the east bank of Lingding Ocean. Its coastline is about 6 km long and the water depth near the shore is Favourable. Across the bay is the ' New Territories " of Hong Kong. The port is at a distance of 22-23 seamilesaway from center of Hong Kong and 80 seamiles to Huangpu Harbour of Guangzhou, its highway links with Shen-Guang Highay. Since 19 79 China Merchants Group of the Transportation Department, began to set up Shekou Industrial Zone, the port has been developing and flouri­shing in business. With 15 large or small berths in all, the present portline is 2600 m, and the annual cargo throughout is over 3,000,000 tons and the annual passenger traffic is about 2,000,000 persons. Equalling a medium-scale seaport, it has been officially approved as an oceangoing transit port by the ministry of Transportation. The construction of Shekou port is chara-terized by the self-collected funds and the short construction period. In view of this, the optional plan of the port structure must serve the requirements of simplicity in struture, economy in mate­rial and speed in construction. That accounts for the most application of the sheet piling type to the port in Shekou. Once the project was approved, the cons­truction started. Only within an average period of 7-8 months, a deep water pier was completed and put into operation, which covered series of processes from exploration, designing, tender for con­struction to completion.

Jan 1, 1991

By Donald B. Buddecke

The large walking dragline has been the most commonly used overburden-stripping equipment in Texas lignite mines. These draglines, operating on the highwall side of the pit, can excavate to a depth of 45 m. Considerable overburden rehandling is required beyond 30 m and may reach 100 percent by 45m. As pit depth increases, dragline operation also becomes more complex, with two or three passes being necessary to make a cut 30 to 40 m wide. Multiseam operations also require extra passes. At pit depths greater than 45 m, the dragline must be operated also from a spoil bench. This can be difficult in the unstable alluvial deposits in which lignite occurs.

Jan 1, 1985

By Batric Pesic

Calcium silicate slag (Di-Cal) and magnesium oxide condensate (MgO) are the by-products of magnesium smelting operations, As these oxides have acid neutralizing and metal precipitating properties, it was decided to examine their reactions with (a) individual heavy metals and (b) with a mixture of metals in solution, The resulting solid reaction products were further tested with respect to the stability of the contained metals, The stability of the solid precipitates were examined as a function of the method of precipitation and as function of the solution pH With respect to the method of precipitation, the performance of Di-Cal and MgO was compared to the performance of lime, an industry standard for heavy metal precipitation, Four different pH solutions (4,0, 5,0, 7,0 and 1 LO) were used to study the effect of pH on the stability of the precipitates. It was found that Di-Cal, in most cases, produced the most stable precipitates and thus, outperformed lime, Metal precipitates prepared by the addition of MgO were the most soluble for each metal studied, except for Se,

Jan 1, 2001

By Benjamin F. Merembeck

A mutispectral scanner (MSS) obtains remotely sensed data of the earth's surface in vector form, one vector element for each spectral sensing band of the MSS. Data generated by either airborne or orbiting MSS systems are organized in a lattice of scan lines and elements within scan lines. Each element, called a pixel, is represented by an observational vector and corresponds to a relatively small specific area on the ground. The total observations for a sensed scene frequently are in the millions and are composed of a number of populations, each representing a different land form category. Based on samples from the populations, the mean vectors, or spectral signatures, and the covariance matrices for the categories may be estimated. From these, an among category covariance matrix and a combined within category covariance matrix can be found. The total among category variance is the trace of the among category covariance matrix. Canonical analysis finds a linear transformation matrix such that the first transform variable accounts for the maximum possible part of the total among category variance. Similarly, the second transform variable, orthogonal to the first, accounts for the maximum possible part of the remainder of the total variance, and so on. Such transformation often results in over 95 percent of the total variance accounted for in the first three canonical variables, even though the initial number of spectral bands exceeded twenty. Transformation of bulk data into three canonical variates allows color map products to be developed by assigning each variable to a different basic color. Such color products are believed to be more useful for photo-interpretation than color products resulting from any combinations of three of the initial spectral bands.

Jan 1, 1977

By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can’t meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Jan 1, 2015

By K. Poorhaydari, B. M. Patchett, D. G. Ivey

In this paper, some applications of carbon extraction replicas, as samples for transmission electron microscopy (TEM), are discussed. Modern high strength microalloyed (HSMA) steels, used as structural or pipeline materials, have very small grains with substructures. Replicas used in TEM can resolve the grain boundaries and can be used for grain size measurements in cases where the small size of the grains pushes the resolution of conventional optical microscopes. The grain size variations obtained from replicas correlated very well with mechanical property variations, indicated by hardness, in the fine-grained heat-affected zone and base metal of some welded HSMA steels. Replicas are also very suitable samples for precipitate examination with analytical TEM. Advantages and limitations of the application of replicas, as well as some corrections for the estimation of the volume fraction of fine precipitates, are discussed.

Jan 1, 2005

By Mansour Asri, Philippe Somogy, Youssef Daffi, Amor Karim

Very few cases of Cast Blasting use in phosphate mining are reported. However, in open-cast coal mining, Cast Blasting is a common practice. And yet, the geological structure of both types of deposits is similar. Accordingly, advantages for phosphate open-cast mines are manifest, especially as future conditions of phosphate deposits fit quite well with the approach.

Jan 1, 2015

By J. R. Andrews, R. P. Young, J. M. Reyes-Montes

"Microseismic monitoring provides insight into the location and extent of rock-mass fracturing induced by cave mining, enabling interpretation of the cave profile and validation of predictive numerical models. Source location uncertainties can lead to misinterpretation of the inferred characteristics of the fracture network. One principal source of uncertainty is the velocity model used to invert the location algorithm. Large-scale 3D numerical models of modulus changes across a caved mass can represent such complexities in the location algorithms, allowing more accurate interpretation of the microseismic activity. A Northparkes mine case study applies this advanced approach to microseismic data interpretation.RÉSUMÉ Le suivi microsismique fournit des renseignements sur la localisation et l’étendue des fractures de la masse rocheuse induites par l’exploitation par blocs foudroyés; cela permet d’interpréter le profil de la chambre foudroyée et de valider les modèles prédictifs numériques. Les incertitudes quant à la localisation de la source peuvent conduire à des mésinterprétations des caractéristiques inférés du réseau de fractures. Une des principales sources d’incertitudes est le modèle de vitesse utilisé pour inverser l’algorithme de localisation. Des modèles numériques tridimensionnels à grande échelle des changements du module d’élasticité à travers une masse foudroyée peuvent représenter de telles complexités dans les algorithmes de localisation, permettant ainsi une interprétation plus juste de l’activité microsismique. Une étude de cas à la mine Northparkes applique cette approche avancée à l’interprétation des données de microsismicité."

Jan 1, 2016

By Steve Custer, Chris Bennett, Patrick Garretson, Glenn Dobby, Jacques McMullen

"Barrick Gold is in the process of expanding one of its grinding circuits at the Goldstrike property as a response to both increasing ore hardness and increased ore sensitivity to finer grinding as it relates to gold recovery. The plant currently operates with two parallel grinding lines, each with a SAG mill, a pebble crusher, and a ball milling arrangement. As part of determining what additional equipment was to be required, a CEET evaluation program was conducted (CEET is an acronym for Comminution Economic Evaluation Tool). The work included: Development of a hardness ‘model’ for the ore body, as described by SAG Power Index and Bond Work Index;Site benchmarking surveys to fine tune the SAG and ball mill calibrations within CEET;Conducting CEET studies to examine the process options;Comparing CEET results to standard grinding circuit design techniques.The recommendation of the study, presently being implemented, is the installation of an additional ball mill on one of the two grinding lines. This paper reviews the sizing techniques applied, providing a CEET case study for circuit performance analysis and circuit design. OVERVIEW OF COMMINUTION AT GOLDSTRIKEOre feeding the autoclaves at Goldstrike are first processed through two parallel grinding lines. Both lines use SAG mills with cone crushing of pebbles followed by ball milling. A summary of the key circuit parameters is provided in Table 1. Line 1 primarily processes underground Meikle ore, although when no Meikle ore is available, it processes open pit Betze ore. Line 2 processes Betze ore exclusively. The Mill Line 1 P80 objective for Meikle ore is 74 microns. According to the recovery optimization analysis, a P80 of 90 microns was recommended for Betze ore. The potential however exists to perform co-mingling of both ore types and feed the higher grade Betze ore to Line 1, in which case the P80 of 74 microns would be retained."

Jan 1, 2001

By B. C. Paul, R. Q. Honaker, M. Huang

Froth flotation is now, the most commonly used method for cleaning fine-coal fractions in coal-preparation plants. Past research and industrial practice have demonstrated that froth flotation achieves excellent separation efficiencies for fine coals having only a small fraction of middling particles. However, the efficiency of froth flotation decreases sharply as the concentration of middling particles increases. This is due to the flotation of high-ash particles that have a small amount of hydrophobic coal present at the surface. Because gravity-based processes are much more efficient for the treatment of middlings, the application of centrifugal washing for fine-coal cleaning was studied with an emphasis on the primary cleaning of fine-circuit feed. Results are shown of a parametric study that used a semibatch Falcon centrifugal concentrator. The results of the study revealed that separation performance is a function of particle size, bowl geometry, feed solids content and feed rate.

Jan 1, 1996

By L Cooper, J Sharma, M J. Hendry

Thick clay tills below potash mine tailings and brine ponds are important natural barriers protecting fresh water aquifers in Saskatchewan. Centrifuge modelling was applied to assess geochemical processes and impacts of dilute brine (0.1 M NaCl) migration through clay till core samples obtained from non saline, unoxidised clay till at a mine site. At accelerated gravity of 876 + g, during each day of centrifuge modelling, flow driven through a 52 mm length core simulated transport through a 45 m thick clay over ~2100 years. Hydraulic conductivity, monitored continuously before and during brine permeation, was low and relatively constant (8.5 + 10-12 m/s), confirming that confining stresses prevent permeability increase. Core density and porosity measurements confirmed that reactive transport occurred under realistic in situ conditions. Breakthrough (defined by C/C0 = 0.5) of non-reactive Cl- occurred at 25 days. The slight delay for Na+ breakthrough, associated with small increases in Ca2+ and Mg2+ concentrations in the effluent were attributed to ion exchange, but carbonate reactions were relatively unimportant. Cation exchange analysis of core samples was inconclusive without corrections for porewater Na+ and carbonate dissolution. Geochemical processes that were observed during centrifuge modelling were successfully simulated using the 1D geochemical transport code PHREEQC. Solute transport was dominated by diffusion with limited ion exchange to delay Na+ migration. Brine would not break through a 45 m thick clay for tens of thousands of years. Based on these findings, the thick clay till at this site, if laterally extensive and undisturbed by drilling activity, is likely to act as an effective natural barrier to vertical brine migration over the long term.

Jan 1, 2003

By D. Yamada, T. Tanaka, N. Inouchi, J. Nakahigashi, H. Yoshimura, T. Nonishi

The use of cereal food materials as lubricants was investigated in an attempt to develop nonpolluting lubricants. Suspensions of wheat flour in water and other types of cereal food lubricants were prepared and their friction coefficients measured. The results indicate that a cereal food lubricant containing 30% lipids, 2% proteins, 60% carbohydrates and 0.6% calcium carbonates has the lowest friction coefficient for a sheet (cpTi-1). As example applications, the lubricant was tested with a forming press and a screw-fastening device. In both applications the cereal food lubricant performed relatively well in comparison to conventional lubricants and thereby has potential for practical applications.

Jan 1, 2006

By Joanna Bzówka

Nowadays, there are some new requirements for the supermarket floors. The floors are loaded by high point- and moving-loads. In spite of this fact, it is necessary to ensure the stiffness of the floor and the stiffness of its support. When pile foundations are designed in the case of weak soil, the piles are recommended under the foundations of the supermarket and also under the floor layers. The example of foundation of a typical supermarket located on long­standing municipal dumping ground is presented. Indirect foundation - CFA piles, 0.5 m in diameter and 4.5 to 20.0 m long, was de­signed. Fifteen trial loading tests were carried out.

Jan 1, 2006

By L. M. Oshinowo

The incorporation of advanced analysis tools, such as CFD, into the process plant design process has become possible through advances in commercially available computational fluid dynamics software and faster computers. Multiphase modeling is now typically employed in the design phase of process plant design at Hatch. The multiphase models include Lagrange-Euler and Euler-Euler treatment of the multiple phases. Additionally, mixture models with interface-sharpening algorithms are applied to the prediction of free-surface flows in complex geometry. CFD is applied to applications where traditional design rules are not applicable. The additional rigor of CFD modeling in 2D and 3D allows process engineers to come closer to realizing true virtual plant design. The objective of this paper is to outline the benefits and pitfalls in the application of multiphase modeling for rigorous design. Several application examples in the hydrometallurgical field will be presented.

Jan 1, 2005

By Takashi Sasaoka

Chain Conveyor Cutter (CCC) is a chainsaw-type machine and originally developed for the construction of underground walls and/or ground improvements. CCC was developed from the accumulated technology of coal mining, combining the cutting technology of a shearer and the fuctions of chain conveyor. The CCC can cut harder soils and soft rocks, and vertically mixes the cut soils/rocks with cementing material selected through the discharging port installed at the bottom of the machine. In Indonesia, highwall mining trials have already been conducted in several coal mines. However, full-scale and regular operations have not been done yet due to the ground and machine control issues from their geological conditions. In order to overcome these problems, the application of CCC to highwall mining systems was proposed, and its applicability and technical issues to be solved were investigated in this research. This paper discribes the characteristics of CCC system and discusses the application of CCC to highwall mining systems.

Jan 1, 2012