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By Dale Preece, Stephen Chung, Qian Liu

Stoping is one of the widely adapted methods in underground mining. In this method, fanned or parallel holes are often drilled from a top sill down to a sub- level in the ore zone and blasted ring by ring into a stope for excavation. At Brunswick Mine of Canada, this technique has been used daily in conducting production blasts. However, when mining into the West Ore Zone, it has been identified strategically that a mass stope blast, involving the blasting of rock from the 3-sub level down to the 1-sub level, should be considered to ensure the safe operation and regaining of access to the trapped main ore zone. The challenge of this mass blast lies in the control of ground vibration and precise timing for blasting 800 holes drilled in six blocks from three different levels within 6.5 seconds, to allow sufficient void to be created in each level for the muck moving in order from the upper to the lower levels without bridging. This paper describes stope blast simulations using a discrete element computer code for modeling blast-induced rock displacement in conjunction with a precision electronic programmable delay timing system for various stope geometries including a drop raise blast at the start of the mass blast. The modeling concept is also described in the paper.

Jan 1, 2003

The title of this address was selected before I had an opportunity to consider in detail the matters that I would like to discuss. Accordingly, I chose a very broad subject-so broad indeed that it would be foolhardy for me to attempt to deal with more than a few aspects of it. I do not propose to touch. at all on the developments to date of our mining and metallurgical enterprises, beyond paying a sincere tribute'to the skill and enterprise of those who have established an international reputation for Australian mining and metallurgy. I would rather look ahead and discuss certain factors that will play a decisive part in the future development of our mineral resources. I do this in no dogmatic spirit, and I hope that my remarks may lead to discussions which will stimulate action where it is needed.In recent years my colleagues and I have been forced by circumstances to give consideration to problems in the fields of mining and geology, and in process metallurgy, which lie outside the scope of our own research work. People come to us with metallurgical problems because they know of no more appropriate place to go, and it is distressing to have to inform them that it is nobody's job to offer them advice and assistance. I want to suggest to your Institute that it should press strongly for the provision of properresearch facilities for the mining and metallurgical industries, such as aready exist in most enlightened countries. In such countries, those connected with the development of mineral resources are able to obtain information and advice from Geological Surveys, Mines Departments or Bureaux of Mines, which offer far more comprehensive services than are available in this country.Before discussing specific technical problems of the mining and minerals industries, I shall enunciate certain general principles that I believe should be followed in respect to the technical side of the development of all Australian industries. The problem can, I suggest, be considered in three parts-technical education production, and research. I shall confine my remarks mostly to the research aspect, for it is with this that I am most familiar.For the efficient development of any industry in Australia, it is essential firstly that We should learn what is going on abroad, and secondly that we should simultaneously conduct independent research. In the latter sphere the Governmeht'departments and the private companies' or groups of companies should have complementary functions, the former concentrating on problems common to a number of companies or industries, and the latter on their oWn individual problems. It is essential to the continued existence of Australian industry that both company and govern...

Jan 1, 1944

By P J. Fourie, J R. Walklate

Gravity separation techniques have been in use in the mineral sands industry for decades; from the Reichert cone to Wilfley tables, Wright sluices and the Kelsey Jig, all attempting that elusive perfect gravity separation. Just as the gravity separation industry evolved, Richards Bay Minerals also evolved in their use and approach to gravity separation. This paper discusses the history of gravity separation at Richards Bay Minerals and briefly comments on future developments. History Primary Concentration Richards Bay Mineral?s (RBM) first mining concentrator and mineral separation plant commenced operation in 1977 to process ilmenite, rutile and zircon bearing dunal deposits along the northern Natal coast. The orebody contained a greater proportion of non-valuable magnetic heavy mineral in the SG range of 3 to 4 compared to West Australian and Florida USA deposits, making mineral separation more difficult(1). The deposit was mined using two dredges feeding a floating 2000 tph concentrator. Concentrator feed was screened and fed to two four-stage circuits consisting of primary, scavenger, cleaner and recleaner Reichert cones [see Figure 1]. The primary units were fed at a rate of 80 tph and a density of 60% solids by weight.

Jan 1, 2006

By Kristineq Pankow

The August 2007 Crandall Canyon mine disaster raised national awareness of mining-induced seismicity (MIS) in Utah as well as general interest in how seismic monitoring might improve mine safety in the region. Unlike the situation in most other mining areas in the U.S., local seismographs in Utah?s Wasatch Plateau (WP) and Book Cliffs (BC) coal fields are an integral part of a modern real-time earthquake information system developed by the University of Utah Seismograph Stations (UUSS) as part of an Advanced National Seismic System. The UUSS earthquake catalog contains a continuous record of MIS at all active mine sites in the WP-BC region since 1978 (more than 18,000 seismic events = M 4.2). We describe characteristics of MIS and current seismic monitoring capabilities in the WP-BC region. We then demonstrate, using MIS from an example Utah coal mine, the ability to refine event locations with estimated absolute errors of ~200 m or less using a combination of (1) a double-difference relocation methodology and (2) ground truth information provided by mine operators. This approach enables sufficient spatial resolution to correlate MIS with mining activities, providing a useful tool to help improve mine safety.

Jan 1, 2008

Lean Iron Ore Beneficiation in India

Sep 13, 2010

By Yoshiharu Tanaka, Toshiyuki Ichijo, Masaaki Yamamoto

We utilized electronic detonators (EDs) to investigate the effect of high detonator delay accuracy on overbreak, remaining rock damage, and surface smoothness, in comparison with that of long-period delay detonators (0.25 sec interval) PDs. The experiments were conducted in a deep mine, in a test site region composed of very hard granodiorite with a seismic wave velocity of about 6.0 km/see and a uniaxial compressive strength, uniaxial tensile strength, and Young's modulus of 300 MPa, 12 MPa, and 73 GPa, respectively. The blasting design was for a test tunnel excavation 8 m in cross section, with an advance per round of 2.5 m. Five rounds were performed, each with a large-hole cut and perimeter holes in a 0.4-m spacing charged with 20-mm-diameter water gel explosive to obtain low charge concentration. EDs were used in the holes on the perimeter of the right half, and PDs were used in all other holes.

Jan 1, 1995

By David Estrella, Hector M. Lizama, Jhonny Carrión

"Microcel™ sparging systems were installed on one column of the molybdenum cleaner circuit and one column of the copper first cleaner circuit at Antamina. The Microcel™ system is known to generate finer bubbles than jetting-type spargers, and smaller bubbles have been associated with higher recoveries in flotation. Alternating tests were carried out on the molybdenum column, using either jetting-type spargers or the Microcel™ system. Experimental conditions of gas flow rate, wash water rate, and froth depth were tested. Use of Microcel™ decreased the bubble sizes from 2.6-2.9 mm to 1.5-2.0 mm. In addition, Microcel™ improved both unit molybdenum recovery and unit molybdenum concentrate grade. In the copper first cleaner circuit, side by side tests were carried out that compared the Microcel™ column with a parallel columns fitted with jetting-type spargers. Best results were obtained at manifold pressures of 260-290 kPa, where bubble sizes of 1.6-2.6 mm were observed. In either copper or molybdenum flotation, the Microcel™ system required only 50-60% of the gas flow used by jetting-type spargers.INTRODUCTIONAntamina is a copper-zinc mine located in the Peruvian Andes. Compañía Minera Antamina is owned by BHP Billiton (33.75%), Xstrata (33.75%), Teck Cominco (22.5%), and Mitsubishi (10%). The mine was commissioned in 2001 with a capital investment of US$2.3 billion, and has a nominal 100,000 t/d mill capacity. Mining, milling, flotation, and tailings impoundment take place at the mine site, which sits at an altitude of 4,300 m above sea level. The deposit is a polymetallic skarn ore body with intrusive phases of quartz-monzonite porphyry into Cretaceous aged limestone [Evans et al, 2005]. Ore body thickness is 100 to 150 m and has the shape of a flat-lying crescent. Copper is present mainly as chalcopyrite with a minor bornite component. Zinc is present as sphalerite. Molybdenum is present as molybdenite. Some lead, bismuth, and silver are associated with the sulphides. The deposit is currently classified into six main ore types [Dechert, 2006], grouped into two categories: copper and copper-zinc. The mill produces four concentrate types: copper, molybdenum, zinc, and lead-bismuth. Copper, zinc, and lead-bismuth concentrates are transported by pipeline down to the port of Huarmey. Molybdenum concentrates are bagged and trucked to port."

Jan 1, 2008

By B. E. Ydstie, B. F. Lund, K. R. Løvåsen, B. A. Foss

The paper presents sensitivity analysis for a dynamic model of submerged arc silicon furnaces. The model we study, called ?Simod?, was developed by Elkem in cooperation with NTNU and Sintef. It is today a much used tool in Elkem for operator training and analysis of the dynamic behaviour of the silicon production process. The aim of our work is to bring the simulator tool closer to industrial practice, and construct a mechanism to adapt the model to the behaviour of a running process, online. The paper presents the results of the sensitivity analysis that has been undertaken for important parameters in the Simod model. The parameters associated with the process inputs are electric power loss, loss of fixed C and reactivity of carbon. The output signals that have been investigated are fed quartz, tapped silicon and silica. The paper also interprets the results of the sensitivity analysis in a process operation context.

Jan 1, 2004

The Skorpion Zinc Project demonstrated the viability of the production of zinc from non-sulphide (commonly called ?zinc-oxide?) ores, using the leach/solvent extraction/electrowinning process route. The success of Skorpion raised the profile of a number of other zinc oxide deposits, considered to be similar. However, a study of three such deposits demonstrates that the application of whole-ore-leaching may be limited and that the concentration of zinc, or at least the separation from acid-consuming gangue minerals, prior to leaching is essential to the successful recovery of zinc from these deposits. The recovery of zinc is dependent on an understanding of the geology of the deposit, the mineralogical association of zinc minerals with gangue minerals (Boni, 2005) and limitations of mining practice. Flow sheet development and the associated metallurgical test work to derive an economically viable treatment route from two of these deposits are discussed. Key parameters affecting zinc recovery by gravity separation and flotation are presented, demonstrating that even minor differences in mineralogy have a profound impact on zinc recovery and reagent consumption. The study also deals with the determination of appropriate design parameters through metallurgical mapping of the dense media separation process.

Jan 1, 2008

Ferrochrome is the major chromium source for stainless steel production, and submerged-arc furnaces (SAF) are most commonly utilised to smelt chromite ores into ferrochrome by using suitable carbonaceous reductants such as coke. Because of the complexity of feed structure and electrical-thermal-chemical interactions, there exist large gradients and wide distributions of temperature, mineralogy and other process variables in the furnace. This leads to various zones in the furnace, and different reduction mechanisms. Control of the furnace is thus often difficult due to the complicated physical and chemical situations in the furnace. The temperature profile in the submerged arc furnace has a great influence on the reduction rate and the production efficiency. Therefore, the energy generation through electrical arcs submerged in the solid feed and its distribution within the packed bed play an important role. In the present paper, an overall process model is illustrated to simulate inter-linked transport processes of fluid flow, heat transfer and reduction kinetics within the submerged arc furnace. The application of reaction kinetic data to simulate the chromite pellet/lumpy ore reduction with CO gas is presented and further adjusted to provide a submodel for a flow and heat transfer simulation for the packed bed by using computational fluid dynamics (CFD) technique. The comprehensive process model is aimed to simulate materials and gas flow, temperature and energy distribution throughout the furnace system. A preliminary model for gas flow and temperature distribution for the upper part of a 20 MW furnace (the packed bed) for high carbon ferrochrome production has been developed under simplified conditions. The integration of the reaction kinetic model into process simulation, and the future vision for a more comprehensive process modelling are discussed. It is expected that better understanding of the furnace insights through process modelling will help process optimisation and furnace control.

Jan 1, 2004

By J. F. Curtis

In the synopsis, the author concludes that ?high levels of seismicity do not coincide with high rockburst rates?. Implicit to an appreciation of this statement is the necessity of a common understanding of what is understood by the terms: ?high level of seismicity? and ?high rockburst rates?. With respect to the former term there is no difficulty in that the level of seismicity is traditionally measured in terms of the Richter Scale. The latter term however presents a problem in that the author defines it as a particular sort of seismic event?viz: ?Rockburst? is understood as a seismic event that causes damage to an underground excavation with subsequent injury, loss of material/equipment or production shifts? (p. 322). No scale is given of the amount of: ?excavation damage ?level of injury ?material/equipment loss ?production shifts lost whether separate or cumulative, for a particular seismic event to be classified as a rockburst. A further difficulty arises in that in common usage the words ?rockburst?, ?seismic event? and ?earthquake? are all used to describe the same event.

Jan 1, 1999

By W. C. A. van Niekerk, M. H. Fourie

The carcinogenic potential of chromium (VI) has been the subject of numerous environmental and occupational studies, from which many regulatory efforts emanated. Besides the regulation of levels of known toxic substances (e.g. Cr (VI)), the classification of dusts for regulatory purposes has thus far depended on broad definitions of particle size, mainly used to distinguish only between inhalable and respirable particles. In the past, ultrafine particles (less than 0.1 µm diameter) (PM0.1) were often regarded as a non-issue, because it was believed that significant doses would not deposit in the lungs. A growing body of scientific data is indicating that ultrafine particles are more toxic than their coarse counterparts. Increased toxicity can be related to the unique dosimetric aspects of the deposition and disposition of inhaled ultrafine particles. Secondly, ultrafine particles have a larger surface area per given mass. The increased surface area can act as a carrier for co-pollutants, specifically transition metals (including chromium) that could form a coat on the particle surfaces during particle formation. This suggests that the presence of ?inert? ultrafine particles in the environment may enhance the potential for exposure to reactive airborne compounds, including Cr (VI). These factors are particularly important when information on occupational epidemiology is interpreted. It is desirable to consider the particle size distribution, for example when occupational exposure to hexavalent chromium compounds is assessed. Since ultrafine particles are more toxic than coarse particles with the same chemical composition, it could be speculated that cancer slope factors might be related to particle size distribution. This is relevant not only to carcinogenic chromium compounds, but also basically for any particle-associated toxicants. In general, the probability of developing health effects associated with occupational toxicants is likely to be higher when these are associated with the ultrafine particle range.

Jan 1, 2004

By R. P. H. Willis

For technology transfer to be successful a process, from research to full scale application, has to be followed. This paper describes such a process and how it is applied in practice. Some of the ?do?s? and ?don?ts? are highlighted. Recommendations are made on how to communicate existing knowledge and to ensure that a framework exists to effectively plan future projects with final technology transfer objectives firmly in place. The Impact Ripper System is used as a case study to illustrate lessons learned. Key words: Technology transfer, implementation

Jan 1, 2002

By S Jokanovic

At New Zealand Steel MiningÆs Waikato North Head operation a Bucket Wheel Excavator û shiftable conveyor mining system is used to excavate titanomagnetite bearing sand and clay. The system utilises two Bucket Wheel Excavators and two Beltwagons with a two shiftable bench conveyors and two common trunk conveyors to deliver material to a processing plant. The original system was commissioned in 1984 as a high capacity, low cost method of excavating. In 1996 a second Beltwagon was purchased, increasing the flexibility of the mining system.

Jan 1, 2002

The trend for using larger equipment in open pit mining to achieve cost effectiveness raises the question about the optimum economic point of scale in the current world of globalization. The present paper treats this question through the prism of a new methodology of assessing the impact of the size of production equipment on the economic outcomes of coal mining ventures. The methodology incorporates a production scheduling optimization model that implements both principles of mine planning, coal quality optimization and waste deferment. The implementation of the waste deferment principle dealing with the spatial and time aspects of the mine sequence arrangement allows the adequate modeling of the optimality of production equipment scale through the use of mine investment parameters, such as, purchase and ownership costs and discounted cash flows analysis. A case study is provided to illustrate the applicability of the new methodology.

Jan 1, 2004

By F. T. Cawood

One of the consequences of globalizing mine finance is a necessity to apply uniform accountancy and valuation standards that are clearly understood and consistently applied by the global investment community. However, each country has unique circumstances, which sometimes make it difficult to align domestic practice with international requirements. South Africa is no exception and issues such as its political history, a taxation regime enforcing different rules on different mineral producers and a unique mineral rights ownership distribution, are barriers to internationalization. The economy is in a transitional phase as a result of the many and diverse policy documents following the change in political dispensation in 1994. Many of these documents have recently been implemented through new legislation and, in the case of mining, negotiations are continuing in order to ensure an acceptable outcome. This paper discusses the challenges that the South African minerals industry faces in the field of mineral property valuation. It draws on international experience and includes a discussion on the unique considerations that the South African mineral property market must take into account in establishing a code for this purpose, as such a code could later be aligned with international practice.

Jan 1, 2004

By Gordon Revey

Over ten million pounds of explosives are used daily to blast rock in mines, quarries and construction projects throughout the United States. Despite the immense volume of explosives used, serious incidents involving the legal use of explosive materials are rare. Unfortunately, when incidents arise they are well publicized, whereas the great majority of blasting projects-even the most challenging ones—quietly occur without incident or public recognition. Although unfair, media coverage focuses on incidents and/or accidents, and as a result skews the public’s perceptions of our industry. These negative perceptions about blasting profoundly effect our work. Most apparent are the community groups who organize to fight blasting work. However, other impacts are more insidious and have long-term effects on our industry. For instance, planning engineers or government agencies often prohibit blasting to avoid the public’s adverse reaction or because of general fear of blasting impacts. Ironically, as regulations and specifications continue to curtail our industry, the net effect is an increase in the cost of rock excavation. As taxpayers, we suffer needlessly by paying more for government funded construction projects. As blasting professionals we are additionally penalized through loss of work.

Jan 1, 2001

By Gerald G. Johnson

The use of the Scanning Electron Microscope to characterize Coal Mine Dust has been possible because of two circumstances. First, the imaging process of the SEM allows multiple signals (secondary electrons, back scattered electrons, x-ray emission, etc.) to be viewed. Second, the use of a computer to analyze the signals and perform statistical tests on the results. The parameters described are size, shape, chemical composition, mass distributions, and particle thickness. Although the system is intended for particular systems, those of agglomerates (whether tile same or not) are handled by special aspects of the computer programs. The work on fibers is not completed at the time of this report. This work discusses the hardware (developed especially for this process) and software (both on an IBM 360/370 and a PDP 11/20). The latter system allows direct interaction between the operator of the SEM and computer for maximum information at the least time.

Jan 1, 1979

THE Great Cobar Company Limited owns 1100 acres of freehold, which include the Great Cobar Oopper Mine and smelters, the Cobar Gold Mine, the Cobar-Ohesney Copper Mine, and the Great Peak Gold Mines.ORE OCCURRENCEThe ore-bodies in the first three mines-namely, Great Cobar Copper Mine, Cobar Gold Mine, and Cobar-Ohesney Oopper Mine are, speaking generally, lenticular deposits of evidently more or less complete metasomatic replacements of the country rock along a line of powerful faulting. These lenses vary from 150 ft. to 400 ft. in length, and from 20 ft. to 100 ft. in width.

Jan 1, 1919

By W. Barthel, B. A. Dippenaar, J. Malan

In its most basic form, the process of sintering is very simple, and has been in use since the turn of the previous century. However, while the basic process is simple, control of the process relies on a number of extremely complex interdependent process parameters and requires a thorough understanding of the effect of these parameters on production capacity and product quality. Further, as with many other processes, the process parameters and hence design details of visually similar installations are highly dependant on the specific feed materials. While the industry trend has been towards an increase of capacity in order to lower unit production cost, typically in Iron ore sintering plants, this approach is not always possible for other commodities because of the scale of operation. This paper seeks firstly to describe some design considerations of sinter plants; secondly, to report on results from testwork performed with a specific series Manganese ore blends; and last, to relate these results to the design of new small-scale Manganese ore sinter plants.

Jan 1, 2004