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By D. A. Peterson

A research program is currently in progress at the University of British Columbia to determine the potential of composite cable bolt reinforcement in Canadian mines. Several prototypes of glass fibre cable bolts have been tested. Their evaluation consisted of lab testing at the University of British Columbia, United States Bureau of Mines (Spokane) and trial installations at Detour Lake, Winston Lake, and Myra Falls Mines. A market analysis of cable bolts within the Canadian mining industry has been completed. Fibre reinforced polymer composites have a high potential as cable bolt reinforcement in mining applications. They prove to be a viable alternative to steel cable bolting.

Jan 1, 1993

By A. Juganda, Jr. Bogin, S. A. Lolon, J. F. Brune, J. W. Grubb

"A longwall gob is mainly filled with broken rocks from the collapsed roof and becomes a porous medium where explosive methane-air mixtures can accumulate. In bleeder ventilation systems, this mixture can migrate out of the gob into the longwall face and other active areas in the mine during barometric or ventilation-induced pressure changes. When external pressures change, the gob does not perceive this disturbance instantly but with a delay due to air flow resistance in the porous gob material. The delay of gob response to outside pressure changes increases the pressure differential across the gob and may cause an outflow of explosive air mixtures from the gob into the adjacent bleeder entries. With computational fluid dynamics (CFD) modeling, researchers at the Colorado School of Mines have evaluated the impact of gob pressure fluctuations on the outgassing of the explosive gas zones (EGZs), the magnitudes and rates of pressure changes, the volumes as well as the potentials location of outgassing if it occurs. INTRODUCTION The air pressure field in underground mines is controlled by many factors such as operating fan settings, ventilation controls, surface atmospheric conditions, and other local events that can intermittently disturb mine pressure, including blasting, roof falls, or inundations. Mine fan settings are rarely changed. Mine atmospheric pressure fluctuations due to adjustments in ventilation controls occur more often during the mining process. Atmospheric conditions and barometric pressures can generate fluctuations in mine pressure on a large scale. Atmospheric pressures change regularly every day but can fluctuate abruptly and become increasingly hazardous in adverse weather conditions. Investigations conducted in coal mines in the United States, Australia, Poland, and South Africa observed higher methane emissions from the gob during periods of falling atmospheric pressures, which led to mine explosions (McIntosh, 1957; Boyer, 1964; Kissell et al., 1973; Fauconnier, 1992; Belle, 2014; Wasilewski, 2014; Lolon et al., 2015). Falling external pressures are understood to cause potential outflow of explosive mixtures from the gob, while rising pressures may push fresh air into the gob. This phenomenon is widely known as gob breathing. The actual processes that trigger gob breathing are not fully understood, nor are the parameters that contribute to the process. Other major events such as roof falls or fan failures can also change the pressure conditions in the mine. In contrast to atmospheric pressure changes, these events can change mine pressures much more rapidly or immediately. TIME LAG AND GOB BREATHING CONCEPT In a bleeder ventilation system, the pressure in the gob is designed to be lower than that of the headgate entries and the longwall face. Air from the gob and gate entries flows towards the tailgate-bleeder returns. When the external pressures are disturbed, this designed pressure arrangement may change, potentially resulting in increased outflow from or inflow into the gob."

Jan 1, 2017

By Ron Jackson

The report gives a general method for the geological evaluation of a gold deposit. Recognizable parameters associated with gold mineralization are used to develop a model of an orebody. The California Mother Lode is used as an example.

Jan 1, 1987

By A. S. Nhleko, P. R. Lobe, H. Mtegha

"Government’s equity role in the minerals sector is one of the nationalist measures implemented in order to ensure greater control and management of a country’s mineral resources. This paper evaluates the Tanzanian government’s equity participation in the minerals sector from 1996 to 2015. The research methodology included determination of the number of mineral rights, minimum allowable exploration expenditures in prospecting licences (PLs), and forms of equity role of the government. Data was collected and analysed for PLs, mining licences (MLs), and special mining licences (SMLs).The study revealed a number of challenges faced by the Tanzanian government as regards its equity strategy in the mineral sector. One of the major challenges was the secrecy surrounding agreements and contracts entered into between the government and private sector investors, which were concluded via various business ownership and mineral development projects. This secrecy resulted in non-transparency and lack ofaccountability in the mining industry.The financial benefits accruing to the government were inadequately realized, evident through inconsistent payments of corporate income tax and mining royalties by the mining companies. Furthermore, the government does not have solid mechanisms and frameworks for assessing non-financial benefits, thus it is difficult to measure the impact of these factors.It is recommended that the Tanzanian government review the Mining Act and Regulations of 2010 to include the provision of solid mechanisms and frameworks for all forms of government equity role.This paper is based on an MSc research study undertaken at the University of the Witwatersrand.IntroductionGovernments can grant private companies mining rights to extract mineral resources, or take a stake in the companies as well as establish state companies to oversee their interests in the minerals sector. The establishment of a state company to oversee government interests in the mining sector implies the direct participation of government by way of equity participation. Equity participation or role is defined as the holding of shares in an enterprise, company, or asset by individuals or a body corporate (Otto, n.d.; Brown, 2013; Natural Resource Governance Institute, 2015)."

Mar 1, 2019

By D R. Venkatesulu, N K. Nanda

Due to increased production of steel in India, the thrust is now on iron ore producers not only to enhance productivity from existing mines, but to look also into alternative resources, like lean grade iron ores such as banded haematite quartz (BHQ)/banded haematite jasper (BHJ), which are available in abundance but not yet utilised for want of suitable process technology. In this context, BHJ ore from the Bellary-Hospet sector was collected and subjected to detailed physical, chemical and mineralogical characterisation and beneficiation studies. The as-received sample was found to occur physically as alternating layers of haematite and jasper. The chemical analysis of the sample was 41.20 per cent Fe, 39.10 per cent SiO2 and 0.86 per cent Al2O3. Based on the mineralogical observation, haematite was found to be the lone ore mineral and jasper was the major gangue mineral. The microscopic observations revealed that the ore minerals liberate at a top size of 0.150 mm. Guided by the characterisation results, indicative tests were conducted using gravity and magnetic separation equipment, namely, Floatex«, gravity slime table and wet high intensity magnetic separator (WHIMS). The results indicate that it is possible to upgrade the sample by both gravity and magnetic separation techniques. However, the WHIMS results indicate that jasper grains report to the concentrate at higher gauss intensities. Therefore, based on the encouraging gravity separation results and the availability of new design spirals for treating fine particles, the applicability of gravity spirals for beneficiating BHJ in the liberation size range of -0.150 mm was studied. The sample was ground to a top size of 0.150 mm and was subjected to preconcentration using wash waterless spirals. Tests were conducted at different feed rates, pulp densities and splitter positions. The results indicate that it is possible to upgrade the sample from a feed grade of 41.20 per cent Fe to a preconcentrate ranging from 46 per cent to 62 per cent Fe with a yield ranging from 19 per cent to 55 per cent. The obtained preconcentrate was then subjected to a cleaning stage by using a combination of wash water and wash waterless spirals. The test results indicate that it is possible to obtain a final concentrate assaying 65.75 per cent Fe and 4.75 per cent SiO2 with a yield of 25.9 per cent and an iron recovery of 41.31 per cent. It was concluded that further test work is necessary to increase the recovery and improve the product specification.

Jan 1, 2009

By Paul Staples, Fred Woodcock, Robert Grant, Mike Cooper

"Noranda's Brunswick Mining Division, near Bathurst, New Brunswick, processes 10,500 TPD of complex Cu-Pb-Zn bearing ore. Brunswick uses conventional rod and ball milling techniques to achieve a flotation feed size of 75% passing 400 mesh. Over a two year period, testwork was performed using a Marcy pilot plant ball mill to assess the impact of several key variables on secondary grinding efficiency. Four graded mill charges were used to compare balls and slugs at 25 and 29 mm sizes. Data was evaluated by determining grinding rates using a commercially available steady state simulator. Results were critical in Brunswick's efforts to achieve finer grinds while minimizing cost per tonne.IntroductionBackgroundThe Brunswick orebody is an extremely fined grained volcanogenic massive lead, zinc, copper, silver, iron sulphide body between two metamorphosed sedimentary and felsic volcanic rock units. Pyrite content is about 60% with 20% non-sulphide minerals, mainly silica and chlorite.Size reduction at Brunswick is performed by three separate parallel lines consisting of rod mills, primary and secondary ball mill circuits, all in series. The line 3 grinding circuit is presented in Figure 1."

Jan 1, 1997

Evaluation of Grinding Medium Wear in Stirred Mills The standard fine grinding machines in the minerals industry are stirred mills whose performance largely depends on the competency of the grinding medium. Medium wear in stirred mills is one of the key parameters for medium selection. A wear evaluation methodology is developed and applied in this paper to measure the wear rate of river sand using a laboratory batch stirred mill. The procedure is demonstrated by testing the sand medium in a 0.55 kW batch stirred media detritor (SMD). The sand wear rate determined in the laboratory batch mill is successfully scaled up to that determined on a full-scale Metso 355 kW SMD mill.

Sep 13, 2010

By Jamal Rostami, Jürgen Schmitt, Rohola Hasanpour

"Double Shield TBMs can be used in fast track projects for accelerated completion where there is limited information available on ground conditions and there are possibilities of encountering weak ground and shear zones. As such, the shielded TBMs are the primary choice of the machines in long tunnels, but face the possibility of entrapment in squeezing ground, which entails long delays and major risks. This paper examines the possibility of using ground improvement methods to increase ground strength, and thus, increase the capability of the machines to cope with squeezing ground conditions. In this study, 3D finite difference simulation of a shielded TBM in squeezing ground was performed to estimate the operational parameters including required thrust to get a machine out of an entrapment. This analysis was also used to evaluate the possibility of preventing machine jamming by the implementation of pre-excavation ground improvement to increase the strength of the ground. INTRODUCTION In order to face adverse tunneling conditions especially using a shielded TBM in squeezing ground, new shield designs, with extra thrust and torque, step shield geometry with reduced shield diameter from front to the back, and conical shape shields have been used. In addition, many of the new machines have the capability to implement ground improvement at distances up to 50 m ahead of the face in order to reinforce the ground and further increase in their chances to cope with squeezing ground conditions. While these features have been added to the machine, there has not been a thorough evaluation of their impact on improving the chances to avoid machine jamming in weak rocks at high depth, which is conducive to rapid convergence of the ground."

Jan 1, 2016

By Rimas Pakalnis, Catherine A. Dreesbach, Lewis A. Martin

Instrumented cable bolts developed at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health were used in conjunction with existing ground control systems to monitor rock mass loads at Tg Soda Ash's trona mine, Granger, WY. Axial and shear loads were determined to levels of strain gauge accuracy of ±5 N or ±5 micro strain. These gauges were embedded in a remanufactured king wire that replaced the conventional king wire. Cable bolt performance, quality of grout, and installation techniques were also assessed. By using instrumented cables, a mine operator can determine axial load along the cable at predefined gauge locations. These data provide necessary input for an operator to design a safer working environment for miners.

Jan 10, 2000

By Ali Kahriman, Abdulkadir Karadogan, Deniz Adiquzel, Umit Ozer, Suat Bicer, Mehmet Aksoy

This paper presents the analysis and measurements of blast-induced ground vibrations during the construction of Istanbul Kagithane – Piyalepasa – Dolapdere – Dolmabahçe highway tunnels. These tunnels known as T1 and T2 are being constructed by a joint venture group. Within the scope of the study, the particle velocities and frequencies associated with 126 shots during the advancement of the tunnels were monitored and analyzed by vibration monitors at the test site. During the statistical analysis, three different predictor equations widely used in the literature were used to predict peak particle velocity (PPV) and the results and comparison of the predictor equations are presented in this paper. Finally, the particle velocities and frequency values of all blast events were evaluated according to USBM and German DIN 4150 Norms in order to determine the damage risks of the neighboring buildings and structures.

Jan 1, 2008

By J. M. Hong, H. K. Zheng, R. Hu, C. B. Zhou

The Jinping-I double curvature arch dam, located in the middle reach of the Yalong River and with a maximum height of 305 m, is the world highest dam of the same type that has been completed. Since the second and third periods of the reservoir impounding, after which the reservoir water level was raised by about 200 m, a significant amount of leakage was observed out of the drainage holes deployed in the lowest drainage tunnel at the left-bank abutment at EL. 1595 m, with a pressure of 0.3 MPa at one typical hole when it was blocked. In this study, a number of analyses including water quality analysis, digital borehole imaging, tunnel geological mapping and in-situ groundwater monitoring were performed to investigate the source of leaking, the leakage passages and the performance of the grouting curtains. An inverse modeling procedure combining the orthogonal design, finite element forward modeling of the transient seepage flow, artificial neural network and genetic algorithm was invoked to further evaluate the permeability of the foundation rocks whose permeability was underestimated in design, using the in-situ measurements of flow rate and piezometric head. The geological structures that lead to the leakage were identified and the seepage flow behaviors in the dam foundation and the left bank abutment were assessed. Given the connectivity nature of the sub-vertically oriented fractures that induce the leakage event, it is found that some of the drainage holes with relative larger amount of discharge could be closed or blocked for reducing the amount of leakage without remarkably increasing the pore water pressure in the foundation rocks.

Jan 1, 2015

By L Rachmad

Freeport IndonesiaÆs Deep Ore Zone (DOZ) mine is the new underground block caving mine within the East Ertsberg Skarn System (EESS) deposit which started production in mid-2000. The DOZ will produce 25 000 tpd using mechanised block cave mining method and will be the fourth underground mine opened within the EESS deposit. Evaluations were made on former block caving mines at PT Freeport Indonesia (IOZ, GBT Area I and II) in order to design a more appropriate support system. As a permanent support, the thread bar bolt support system is widely used in the DOZ mine. The advantages of this system are ease of operation, quality control and high bond strength. The main problem of this system is the curing time of about 28 days to achieve maximum strength, necessitating the installation of a temporary support for its implementation. In this instance, the system was inefficient in operation and studies were required to find an alternative grouting system. This paper examines the evaluation of thread bar bolt support system and compares the performance of two types of grouting (resin cartridge and cement cartridge) with cement grouting performance. The evaluation is conducted with a pull out test. The advantages and disadvantages for each grouting method, comparison of cost estimation and grouting application in mine scale are presented in this paper.

Jan 1, 2002

By F. Rosenblum, P. Spira

"Self-heating of broken sulphide ore or waste rock underground can lead to ignition and cause serious problems in a mine operation. An extensive study has demonstrated that it is caused by oxidation of certain species of pyrrhotite. Self-heating was found to take place in two stages, first progressing from ambient temperature to 1000C with exothermic formation of elemental sulphur in the presence of moisture and oxygen, and proceeding to a second stage in which the sulphur oxidizes to SO2. Ignition may eventually follow. An apparatus was developed to assess the propensity of sulphide rock to self-heating and the potential for hazardous behaviour. The effect of temperature, time, rock size, and surface treatment with chemicals is presented. On the basis of these results, possible approaches for preventing a runaway reaction are suggested for further investigation.IntroductionThe oxidation of sulphide ore, waste rock or tailings backfill, which may cause hazardous conditions underground through heating, oxygen depletion and, in some cases, fire, is well documented (Farnsworth, 1977; Ninteman, 1978; Rosenblum et al., 1982; Reimers, 1987). The self-heating mechanism, nevertheless, has not been satisfactorily explained. The onset of heating from ambient temperature, in particular, has not drawn the attention of researchers. In the course of a previous study (Rosenblum et al., 1982) aimed at finding a method to assess the hazard from using sulphide tailings as backfill, the authors developed an apparatus to measure self-heating rate under controlled, near ambient conditions. This has since provided decisive information in backfill investigations in the Noranda Group.The test methodology devised for tailings failed to predict self-heating in a broken waste rock known to be active. Upon repeated testing, however, a freshly crushed sample began to exhibit appreciable heating and oxygen uptake (Fig. I). After 14 tests, the self-heating rate reached a plateau of about 4O°C/h and then fell progressively to < 5°C/h after 30 tests. It was hypothesized that weathering in the presence of moisture and oxygen during testing had caused the onset of self-heating. Active tailings, on the other hand, are exposed to natural surface oxidation and need not be weathered to show heating. Based on this finding, a new apparatus was developed capable of simultaneously weathering a sample of rock and monitoring its self-heating behaviour."

Jan 1, 1995

By Itavahn Alves da Silva, Izabela Diniz Duarte, Carlos Antonio da Silva, Varadarajan Seshadri

Mathematical modeling using computational fluid dynamics has been employed to assess the thermal losses in a steelmaking ladle. Thermal losses lead to thermal stratification and convective flow inside the ladle. The effects of preheating, mineralogical and physical characteristics of the lining as well as thickness of slag cover have been studied and the results obtained from application of the model have been discussed.

Jan 1, 2016

By P. C. Schutte, N. B. Strydom, A. J. Kielblock

Three groups of unacclimatized men were subjected to five-day climatic-room procedures at wet-bulb temperatures of 29,30, and 31 C respectively. The findings indicated that individuals reach a satisfactory level of heat acclimatization for work in environmental temperature conforming to those at which they were acclimatized. It is, therefore, superfluous to acclimatize men at wet-bulb temperatures that exceed those at which they are destined to work. These methods of acclimatization can be linked advantageously to heat-tolerance testing at mines with suitable underground temperatures.

Jan 1, 1983

By Gomm SA

The Mount Tom Price Concentrator, which contains a heavy medium cyclone plant for beneficiation of the -6+0.5mm fraction of low grade iron ore, is described. Testwork was carried out on an opportune basis over a period exceeding twelve months, to evaluate the separation performance of the heavy medium cyclones. Plastic density tracers were used and ore samples were taken and analysed. The effect of operating medium specific gravity (S.G.) on the separation parameters, the iron grade of the sinks product, and the mass and iron recoveries were investigated. Also examined were the differences in perform- ance between particles of different size. The implications of the findings for plant oper- ation are discussed.

Jan 1, 1987

By M. Guzman, S. B. Thais, M. F. Obispo, M. R. Arribasplata

One of the greatest environmental issues related to the development of the mining activity is the generation of Acid Mine Drainage (AMD). Many methods have been developed for AMD treatment, being wetlands a good option for heavy metal removal. In this sense, the implementation of artificial wetlands for the treatment of mining effluents would seem to be an environmentally friendly alternative. In this paper, we present the results on the elimination of heavy metals (Cu, Zn, Pb and Fe) using two Peruvian native species such as Schoenoplectus californicus (C.A. Mey.) and Phragmites australis (Cav.) Trin. Ex Steud. The results show that Schoenoplectus californicus preferentially removes copper (82 and 90%), lead (88 and 92%) and iron (28 and 69%), whereas Phragmites australis removes copper (68 and 87%) and zinc (53 and 95%). Likewise, it is observed that the Schoenoplectus californicus mainly retains the ions in its root, copper (89%), zinc (84%) and iron (76%). While the Phragmites australis accumulates iron (62%) and copper (74%) in the steam and root part respectively

Mar 2, 2022

By Jan Luca Grunow, Ansgar Bendiek, Klaus Böde

According to the Markowitz portfolio theory the value of a diversified portfolio is higher than the sum of the parts of a portfolio, which is an important consideration for the correct valuation. This is valid for real estate portfolios as well as for mining assets (or enterprises). This paper analyses the application of the portfolio theory to a diversified portfolio of assets in the real estate industry and draws conclusions on further research work to be done in the minerals industry. The volume of real estate transactions is increasing over recent years. As such, the nature of those transactions is constantly changing and in some cases portfolios become more heterogeneous as they are composed of different property categories, e.g. locations and types of use. This makes their economic evaluation more difficult. This paper focuses on the acquisition of a fairly heterogeneous real estate property portfolio purchased by “Commerz Real” in Germany in Q4 2019. For economic evaluation the widely used Markowitz portfolio theory (Markowitz, 1952) was applied. It was investigated whether diversification effects could achieve added value in the form of a reduction in risk compared to the sum of their individual components. As a result the findings of this research could be applied to other heterogeneous real estate transactions and even to mine property portfolio or PPP1 project portfolio transactions.

Jun 25, 2023

By J. M. Melluish

The metallurgical response of the Point Leamington deposit has been studied. Two series of bench tests were conducted and various ore samples and flotation products were examined using image analysis techniques. The majority of sphalerite and chalcopyrite grains in this texturally complex ore were found to be smaller than 10 micrometers. Copper recoveries were low with losses mainly as fine inclusions in pyrite. Sphalerite recoveries were somewhat better due to a generally coarser habit. Gold and silver recoveries were also low and only solid solution silver was identified in the ore. The deposit shows poor economic prospects unless additional tonnage of high grade zinc ore can be delineated.

Jan 1, 1989

By Julie M. Melluish

The metallurgical response of the Point Leamington deposit has been studied. Two series of bench tests were conducted and various ore samples and flotation products were examined using image analysis techniques. The majority of sphalerite and chalcopyrite grains in this texturally complex ore were found to be smaller than 10 micrometres. Copper recoveries were low with losses mainly as fine inclusions in pyrite. Sphalerite recoveries were somewhat better due to a generally coarser habit. Gold and silver recoveries were also low and only solid solution silver was identified in the ore. The deposit shows poor economic prospects unless additional tonnage of high grade zinc ore can be delineated.

Jan 1, 1989