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By K. N. Han, N. S. Kim, H. Yoon, J. S. Sohn

The leaching behavior of silver and silver oxides in ammonical solutions has been studied. The current study is concerned with an effective recovery of silver from secondary sources such as spent silver batteries. Silver associated with these batteries appears in various forms including metallic silver, argentous oxide, Ag2O and argentic oxide, AgO. The leaching behavior of metallic silver in ammoniacal solution has been studied using an electrochemical mehtod. Oxidants used in this study include hyperchlorite, hydrogen peroxide, bromine and iodine. Results on cyclic polarization and Tafel plots on the silver anode in ammoniacal solutions are presented and the results are discussed. The dissolution rate of metallic silver in ammoniacal solutions is also compared with those of silver oxides.

Jan 1, 2002

By T. Geyer

The Carbon Disclosure Project (the pre-eminent global initiative for institutional investor collaboration on climate change) groups the business risks (and opportunities) related to climate change into four categories: 1. Regulatory risks from tightening legislation (and opportunities for companies that can make the carbon market work for them), e.g. rising costs for carbon and energy-intensive processes. 2. Competitive risks & opportunities generated by a possible decline in customer demand for carbon/energy intensive products (and opportunities from a consequent rise in demand for efficient / low carbon products). 3. Reputational risks from perceived inaction on climate change (and benefits to those perceived to be ?solutions providers?). 4. Physical risks from changes to climatic patterns, e.g. asset damage from extreme weather events; project delays; water scarcity; resource risks as certain crops become no longer viable in certain areas and new supply chains become necessary; and potential human and socio-political impacts. All of these are already having repercussions for businesses in certain sectors and geographies. The understanding of specific impacts of climate change is still evolving but it is clear that climate change will have a material impact on the value of many businesses, either directly or indirectly. Many commentators and analysts consider that rising energy costs are likely to represent the most direct and immediate investment risk that climate change and the resulting regulatory responses will create for business in the near term. However, it is already possible to identify numerous examples of competitive and reputational risks and opportunities that are leading to significant value creation or destruction in business: the success of the Toyota Prius; the rush by the UK?s leading supermarket retailers to ?green? their brands; and the surging fortunes of companies involved in the manufacture of renewable energy generation equipment, are all manifestations of this trend. In addition, the potential physical impacts of climate change are also making themselves felt in certain sectors: an example is the Australian wine industry, suffering after an extreme and prolonged period of drought. THE PROJECT This paper describes a project undertaken for a multinational mining company to examine the physical risks from climate change across its international business operations. The study addressed 163 components of the business and included operating sites (mines, smelters, and refineries), key transport routes (road and rail) and port links. The inclusion of the transport networks and ports is extremely important; key transport routes (e.g. a key railway link) may often be impacted (e.g. by flooding) far more than individual sites due to their large geographic exposure and multiple potential failure points. Extreme weather events causing loss of life and major economic damage continue to be front page news. According to the World Meteorological Organization, January to July 2007 ?was marked by record weather extremes in many regions across the world.? Inevitably, the associated phenomena are starting to impact business and investments, not so much as deal breakers, but in changing the parameters of risk management and the approaches required to devise mitigation measures. EXAMPLES OF EXTREME WEATHER EVENTS No one event can be presented as directly attributable evidence of climate change, however climate change projections suggest that the frequency and severity of many extreme weather events can be expected to increase in a warming world. In August 2003, a heat wave struck Europe, with temperatures as high as 42°C (108°F). As summer temperatures in much of northern Europe rarely exceed 30°C (86°F), the area was unprepared for the disaster, and many thousands of deaths occurred. In August 2005, Hurricane Katrina caused catastrophic damage along the Gulf Coast of the United States, forcing the effective abandonment of south-eastern Louisiana (including New Orleans) for up to two months and damaging oil wells that resulted in increased oil prices. Katrina killed over 1,800 people and caused at least $75 billion in damages, making it one of the costliest natural disasters of all time. This was followed in September, by Hurricane Rita which left 119 people dead along the U.S. Gulf Coast, causing $9.4 billion in damage. In January 2006, hundreds of people were killed when Russia, Eastern Europe and Scandinavia experienced the coldest weather for decades. In summer 2007, dramatic floods in the south central region of England, UK left 350,000 people without drinking water and many without electricity. Transport infrastructure was severely disrupted; combined with floods which occurred earlier in the summer in Yorkshire (North England), the damage is estimated to total over £2 billion. ASSESSING RISKS FROM CLIMATE CHANGE To date, only a minority of companies have attempted to quantify the risks from climate change. However, investors are seeking greater disclosure of climate change related risks and opportunities and it is expected companies that can demonstrate they are prepared for climate change will attract higher market valuations. Climate Change Threats A variety of climate change threats were examined for their potential to have a potential measurable impact on the mining company?s business operations. Those considered most significant were included in the study and are shown in Table 1 (see Appendix A). Certain threats can be considered as being cyclical in nature and the future predictions may suggest a change in the frequency and severity of such events (e.g. storms/hurricanes, rainfall, drought). However other threats are associated with a gradual change over time (e.g. loss of glaciers, loss of permafrost, sea level rises). A slightly different approach is needed to address this differing nature of the threats, as described subsequently. Climatic Regions Much of the research and data associated with climate change is collected and reported on a regional basis. An example of the climate change impacts predicted for a number of climatic regions is shown in Table 2 (see Appendix A).

Jan 1, 2009

By D. Bernabe

The mine scheduling process defines a mining sequence across the life of the mine and stipulates the amount of ore, waste, and specific blocks to be mined each year so that the highest economic return can be obtained under a number of constraints. There are a number of mine scheduling software packages available. Each claims to be the best scheduler by maximizing Net Present Value (NPV) or by minimizing overall mining costs. These mine scheduling programs follow different procedures and scheduling philosophies based on either mathematical or heuristic principles. There was no study in which the mine production scheduling procedures applied by these packages were discussed and compared. This paper evaluates four open pit mine scheduling programs recently developed and compares them in order to determine if significant differences exist among them. The same input data, which consist of a 3-D block model, an economic set of parameters, and the initial surface topography for a operating copper mine in Southern Peru, was used to test each technique. The following programs were investigated with respect to their ability to optimize the NPV for the case study. 1) M821V1 Scheduler by Mintec; 2) NPV Scheduler by Earthworks; 3) Milawa Scheduler by Whittle Programming; and, 4) Fundamental Tree Scheduling Method (FTSM) developed at the Colorado School of Mines. The results from this case study demonstrate that the scheduling software packages, Mintec, Earthworks, and Whittle obtained similar NPV’s, while FTSM scheduler gave a six percent higher NPV than the other schedulers.

Jan 1, 2002

By R. Dillinger

In the environmentally conscious social atmosphere today, reclamation in surface mines has become a main issue to the public and the regulatory committees. In response to this increased attention, many regulatory committees have begun to enact more stringent regulations on surface mining operations. Operations across all spectrums of the industry have seen changes. Recently and most visibly the mountain top removal mines have seen several new regulations focusing on environmental protection. Specifically regulatory committees have emphasized a focus on the methods of reclamation and recovery of layers suitable for vegetation. These layers are the most visible once the operation has concluded. Also, these layers have the most human interaction (farming, hunting, and house development). Often times the new regulations enacted are shifting from a performance base to a standards base. The key differentiator being a performance base dictates the final result while a standards base dictates the method to achieve the result. The very nature of many regulations (especially those that are standards based) not only challenges the physical limitations of the equipment used today, they come with a financial impact. For the purpose of this paper, the model will be a surface coal operation, utilizing draglines as primary overburden movers. The coal seam is ten feet thick, the overburden ninety five feet thick, the pits are 150 feet wide, and the dragline is a Bucyrus Erie 1570.

Jan 1, 2011

By James H. Dye, N. E. Norman

There will be about 300 raise boring machines used worldwide by late 1981, attesting to the acceptance of this drilling system by the mining and construction industries. Over the past few years, many articles have cited the advantages of raise boring: •improved safety; •faster completion of the raise; •elimination of sublevels; •cost reductions; •better structural characteristics of the opening; •labor reduction; and •noise abatement. The relative importance of each advantage varies from mine to mine. When analyzing the total economics of raising, each advantage must be considered. The factors having the most effect on economics are fixed costs, direct costs, and comparative savings versus conventional methods.

Jan 3, 1981

By H. Hamza

Oil sand tailings are disposed of in large ponds in which MFT (Mature Fine Tailings, a stable suspension of fine particles in water) forms after many years of settling. Long-term storage of large volumes of MFT is costly to maintain and also poses an environmental liability. The Advanced Separation Technologies laboratory at CANMET Western Research Centre has worked closely with oil sand companies to eliminate MFT generation by applying paste technology to oil sand tailings. In this process the fine tailings are flocculated to produce a thickened material that has the potential to consolidate to a dry landscape, while warm water is recovered and recycled for reuse in the extraction process. This paper presents some results of an extensive technical program involving bench-scale tests for flocculant selection and continuous thickener pilot tests.

Jan 1, 2002

By Y. Wang, K. S. E. Forssberg, A. Johansson, X. Lu

This paper presents the desulphurisation of a fine graphite powder below 80 µm by high gradient magnetic separation. The removal of pyrite (FeS2) and pyrrhotite (Fe1-xS) from the fine graphite powder was carried out with a modified version of the Sala dry HGMS with vibration assistance. In addition, a comparative study with dry and wet HGMS systems has also been performed. In order to establish the performance of the desulphurisation, a test series of varying parameters such as magnetic induction, matrix type/configuration and vibration were performed. As an equipment/process for removing sulphurous impurities from the fine graphite powder, the dry HGMS is deemed useful and comparative with the wet HGMS.

Jan 1, 2002

By Wern-Ping Nick Chen

Durability risks for underground facilities can be underestimated during design phase as compared to well-known geological risks. However, unclear durability requirements can result in construction schedule delay and change orders. Unlike bridges or buildings, a unified underground durability code or standard does not exist. This paper will provide a durability approach for underground facilities, including degradation modes, mitigations, and compliance measures during construction. In addition, this paper will address how to clearly specify durability requirements in a contract document to reduce disputes during construction and discuss key durability tests that are time consuming and will impact construction schedule if not timely planned.

Jun 23, 2024

By R. J. Sweigard, R. V. Ramani

G.F. Learning The paper by R.V. Ramani and R.J. Sweigard is a wonderful description of the labyrinthine web that has been spun about the mining industry by energetic bureaucrats and politicians over the past 50 years. The remedy for the problem, however, is not more of the same, but less. That may be difficult for the industry to achieve, for it is not a technical solution but a political one. And the current fervor for more detailed planning at all levels of government and private enterprise has become deeply ingrained. The authors recommend the provision of more information about mining and mineral resources to "macro" (i.e., government) land use planners. They apparently overlook, however, the already strong tendency on the part of most government land use planners to consider themselves omniscient. Thus, giving them more information about the technical problems of mining will only make them want to get more and more involved in the "micro" (private, site specific) mine development and production plans of the individual mining firm. In fact, this has already happened at all levels of jurisdiction from municipal to federal government. Examples are legion. The most effective way to ameliorate the adverse impacts of government land use planning on existing and potential mining operations is to: (1) introduce greater flexibility in the definition of land use zones by local and state governments; (2) adopt realistic and relevant ambient environmental performance standards in governing relationships between mineral land uses and concurrent or subsequent nonmining land uses; (3) allow greater leeway for economic considerations in land use decisions in contrast to the explicit legalistic approach now in vogue; (4) recognize that all minerals are not the same and that sand and gravel mining should not be treated the same as underground metal mining, coal stripping, oil field production, or in situ leaching; and (5) eliminate the notion that mining operators should be responsible for determining in detail the use of land by subsequent owners of mined land. This last bit of conventional ethic really makes no more sense than requiring the builders of every shopping center or government office complex to provide detailed plans for the use of that land when its use for shopping or government is ended. Did the builder of Ebbetts Field plan for Brooklyn after the Dodgers went to Los Angeles? Should the developer of the Bingham Pit plan for suburban Salt Lake City after the copper mining goes to Chile? The nation's mining industry must address these questions before further bankrupting itself to provide more data to planners and spending thousands of dollars per acre to create land that when reclaimed is worth only a few hundred dollars per acre. Reply by R.V. Ramani and R.J. Sweigard We thank Mr. Leaming for his valuable contribution. His views on the problems of land use planning and mineral resources are most welcome additions to our paper. As the title indicates, our paper was more concerned with the impacts of land use planning on mineral resource conservation than with the details of the planning process. On the whole, his five recommendations would be helpful for mineral resource conservation. However, we would suggest that the argument he presents for his final recommendation does not address the differences between mining as a land use and commercial or institutional uses. We believe that this difference is the crux of the issue. We share Mr. Leaming's desire to ameliorate the adverse impacts of land use planning. Possibly the most detrimental impact is the loss of mineral resources. Any development, whether mineral or community, that does not give proper consideration to other resources can result in permanent loss or sterilization of resources. With proper planning, some of these losses can be avoided. As our paper indicated, one factor that limits the consideration of mineral resources, and ultimately leads to their sterilization, is the generally inadequate levels of resource characterization and understanding of the unique nature of mineral resources and mining operations. The last point raised by Mr. Leaming is also important. In terms of reclamation and land use planning in mining districts, we certainly do not advocate spending more than what the results are worth. The main thrust of the paper was to explore the avenues for conserving the mineral resources so that, at some appropriate time, the issue of mining and reclamation can still be addressed.

Jan 4, 1985

By D. C. Hogeman

Growing Greener is the single largest investment of state funds in Pennsylvania’s history, allocated to address the Commonwealth’s critical environmental concerns. Signed into law by Governor Tom Ridge on December 15, 1999, Growing Greener will enable the Department of Environmental Protection (DEP) to appropriate nearly $240 million over five years, to watershed restoration and protection, abandoned mine reclamation, and oil and gas well plugging projects. DEP has utilized these allocations in some remarkably innovative ways, as it: involves the cooperation of several state agencies, local governments, and grassroots organizations to address environmental concerns of the Commonwealth, provides funds directly to watershed groups based on locally determined decisions for local watersheds and offers a user friendly process. In three years, over $130 million in watershed restoration and improvement projects have been initiated.

Jan 1, 2002

Steady increases in longwall production have required operators to apply greater quantities of ventilating air in an effort to control and dilute respirable dust. Significant increases in shearer speeds necessitate that longwall supports also be advanced at a faster rate. Both of these factors may contribute to overall respirable dust levels on the longwall face because as supports are lowered and advanced, broken material falling from the top of the canopy is entrained directly into the air stream. To address this issue, the Pittsburgh Research Laboratory collected respirable dust samples from four longwall faces to characterize shield-generated dust. This paper investigates the influence of air velocity and shield advance rates on respirable dust levels. Also discussed are engineering controls currently used to reduce shield dust and alternative controls being investigated by the National Institute for Occupational Safety and Health (NIOSH).

Jan 4, 2010

By R. C. Ford, W. L. Niccoli, J. B. Finley

All mining operations are superimposed on natural hydrologic systems. As a result, mining operations are influenced by natural hydrologic processes and require water management systems to successfully conduct mining activities. Managing water and mining-related solutions is a critical task at all stages of the mine life because of the time-dependent nature of natural and mining-related flows. Effective operation of the mining water management system requires a “systems” approach that integrates the time-dependent effects of all water and mine solution handling components. This paper discusses the concept and application of dynamic systems modeling to address the time dependent nature of mining water management systems.

Jan 1, 2002

In June, 1,334 underground construction and tunneling professionals gathered in Toronto, Ontario for the 2007 Rapid Excavation and Tunneling Conference (RETC). This biennial event, sponsored by SME, is one of the global underground construction industry?s major events. And this year?s RETC was the first one that included the new Underground Construction Association. [ ] (UCA) of SME. In addition, the conference?s exhibit attracted 125 equipment and service providers. The next Rapid Excavation and Tunneling Conference is set for June 14-17, 2009 at Caesar?s Palace, Las Vegas, NV.

Jan 1, 2007

By W. J. Miles

At the beginning of the 20th century, barite was a mineral of minor importance in the USA. Its primary use was to extend lead oxide in white paint. Barite also added the special qualities of hiding power and flatness to paint. Because white lead sometimes turns black or yellow and barite does not, ground barite became a pigment on its own merit. Barium chloride was added to bricks before firing to stop efflorescence when exposed to weather. Barium carbonate or nitrate added luster and brilliance to glass. Barium chemicals were added to refining sugar, enameling iron, making oilcloths and paper collars, and in the manufacture of paper, artificial ivory, rubber and lithopone. Lithopone became a major paint ingredient in the 1920s; its use lasted until the 1950s, peaking at 150,000 metric tons of barite in both 1937 and 1947 for the manufacture of lithopone. Later in the 20th century, titanium dioxide replaced lead oxide, barite and zinc oxide in the coatings industry. In the 21st century, barite is used as a filler, extender, or weighting agent in products such as paints, plastics, and rubber. Some specific uses include its use in brake and clutch pads for automobiles, automobile paint primer for metal protection and gloss, add weight to rubber mud flaps on trucks, and add weight to the cement jacket around petroleum pipelines under water. In the metals casting industry, barite is part of mold release compounds. Because barite significantly blocks X-ray and gamma ray emissions, it is used as aggregate in high density concrete for radiation shielding around x-ray units in hospitals, nuclear power plants, and university nuclear research facilities. Ultra-pure barite consumed as liquid is used as a contrast medium in medical X-ray examinations. Barite is the raw material for barium chemicals, such as barium carbonate, which is an ingredient in faceplate glass in the cathode-ray tubes of televisions and computer monitors. In the 21st century, barite industrial uses account for an estimated 78,000 tons per year in the United States. Another barite use was patented in 1926 by the oil industry. In this patent, barite is primarily used as a non-abrasive weighting agent for drilling for oil and gas exploration and production. As a weighting agent, it provides the downward force in a water based or oil based drilling fluid for cutting through rock with a tri-cone diamond drill bit. In order to minimize the wear on the drill bit and drill stem, minimum abrasion of the weighting agent is preferred. In recent years in the USA, 95% of the barite produced and about 80% on a world basis are used as a fluid weighting material during the search for oil and gas. During the latter part of the 20th century, barite was used in the drilling mud of oil and gas wells, particularly for wells deeper than 2000 meters, and petroleum well drilling demand for barite became the mineral?s major end use during economic expansions after World War II and subsequent increased use of oil and gas in the USA. The profitability of oil and gas production had a strong effect on the number of drill rigs and consumption of barite. The United States was the leading petroleum well drilling country starting in 1970, reaching 4,530 drill rigs in December 1981, and was the largest consumer of barite. In the USA, record highs of about 2.6 million tons of barite produced and 4.3 million tons consumed were reported in 1981. From 1997 to 2006, barite production declined from 662,000 to 589,000 metric tons. However, USA imports increased from 1,470,000 to 2,530,000 metric tons for lump barite. World production of barite increased from 6,780,000 to 7,960,000 metric tons during the same period. Table 1 (see Appendix) lists USA production, imports and exports and world production from 1997 to 2006. Major sources of imported barite include China, India and Morocco. Table 2 (see Appendix) lists the USA imports and price of barite by country. China, India and Morocco are the three largest exporters of barite to the USA and the world. Vietnam is a new producer, beginning in 2006. IMPACT OF CHINA ON DRILLING GRADE BARITE In the 1970s or before, China began supplying barite to the world drilling market in order to help develop their economy. When China first entered the barite export market, their high production volume, low pricing and low ocean transport expenses to the Gulf Coast forced barite producers in the USA to supply only regional markets, such as Battle Mountain Nevada barite for the western and Rocky Mountain states and Canada. Until recently, it was China?s government policy for domestic consumers to use barite below the API 4.20 specific gravity specification, leaving higher grades for export, but this is no longer the case. In recent years the internal demand for barite in China increased tremendously as their economy rapidly developed. China reduced their former 15% VAT tax rebates to 5% for Chinese barite producers, and then eliminated all VAT tax rebates on December 15, 2006. On the supply side, some high-grade barite deposits in China have been depleted. In particular, the low heavy metals sources are less plentiful. Additional mine capacity is being developed, but the new mines are underground and therefore costs will be higher. China?s appetite for other raw materials has tied up a large portion of the world?s bulk vessel fleet, including Panamax vessels (preferred for barite ore transport). Ocean transport freight rates have increased in recent years, and receiving ports in the USA are congested with imports of higher-added-value products. The Panamax Index, which tracks maritime shipping rates, more than doubled in 2006. China has also devalued its currency from RMB8.30 to RMB7.80 per dollar. These factors are driving up the import price of crude and ground barite for drilling. In addition, in the USA, rail congestion and high fuel prices led to higher trucking rates, increasing the delivered cost of ground barite to oil customers. India is the second largest supplier of crude barite to the USA and world drilling market. It produces all of its barite from a single deposit in the Cuddapah region of Andhra Pradesh State. More than 90% of production comes from the State-owned Andhra Pradesh Mineral Development Corp., and the government continues to closely control production, export volumes, and prices. India saw a dramatic increase in barite prices as a result of its last 3-year tender in 2004. However, in 2004 and 2005 their shipments of crude barite to the USA were not significant. In 2005, India began supplying barite pulverized to meet API specifications to the Gulf Coast. In 2006, Indian production was reduced owing to severe flooding in November 2005 that curtailed mining until mid-April 2006. Morocco has been the third largest supplier of crude barite to the USA and world drilling market. In 2003 and 2004 their shipments of crude barite to the USA were not significant. In 2005, Morocco resumed shipment of crude barite to the Gulf Coast and began supplying barite ground to meet API specifications to the Gulf Coast.

Jan 1, 2009

By G. G. Gold

A leach pad’s fluid flow characteristics greatly affect the recovery of metals from heap leaching. However, because there are other factors such as particle size distribution, application rate and method, and chemical reactions to consider, mining companies often overlook potential problems associated with fluid flow until it is too late. In an effort to better understand the dynamics of fluid flow in leach pads, a series of experiments were preformed using temperature probes. A model leach pad was set up using a particle size distribution, fluid application rate, and application method common to modern leaching methods. Variable water temperatures were applied in succession and data gathered from the three dimensional grid of temperature probes built in to the model. Current work is analyzing these data along with visual observations of the model, computer simulations, past mining experiences, and other related research, in an attempt to develop a low cost test that could be performed prior to large scale leaching to determine the fluid flow characteristics of a particular ore. This paper will summarize the work and findings to this point as well as suggest areas of additional related research.

Jan 1, 2004

By M. Hamarat

Freeport-McMoRan Copper & Gold (FCX) is committed to preserving and enhancing biodiversity in the areas in which we operate. As a member of the ICMM, FCX is committed to implement the 10 Sustainable Development (SD) Principles throughout our business. FCX is also a member of the Wildlife Habitat Council (WHC), a nonprofit coalition dedicated to protecting and enhancing wildl ife habitat. In alignment with ICMM SD Principle 7 and our Environmental Policy, FCX has set a performance goal to prepare a biodiversity inventory in 2010 and land management plan by end of 2011 for all active mining sites. In 2010 FCX established a Biodiversity Task Force to assist sites in biodiversity management; optimize use of resources around the globe; implement FCX goals and targets; and align biodiversity programs with ICMM principles and guidance. The task force consists of Environment and SD Department management, scientists and engineers from FCX sites, and WHC staff. The Task Force recently issued a biodiversity inventory guidance document to set expectations and provide consistency across the sites when developing a biodiversity inventory and land management plan.

Jan 1, 2011

Many investigators measured surface forces between hydrophobic macroscopic surfaces using atomic force microscope (AFM). Some investigators observed long-range attractions and attributed them to the presence of hydrophobic forces, while others suggested that they are artifacts of the nano-bubbles and cavities associated with the hydrophobic surfaces. Still others suggested that the long-range attractions are due to the electrostatic interactions between charged patches present on opposing surfaces and hence are unrelated to surface hydrophobicity. In the present work, we have measured long-range attractions between gold- (or silver-) coated surfaces hydrophobized in potassium ethyl xanthate (KEX) solutions at pH 9.2 under controlled potential conditions. The results of our AFM force measurements are consistent with those of the contact angle and voltammetry experiments, indicating that the long-range attractions are hydrophobic forces.

Jan 1, 2012

By David A. Smith

A new generation of reliable, stable, and easy to use bulk emulsions allowing application in tunneling and drift rounds has been developed. This new product group of bulk emulsions has been especially formulated for use in small-diameter holes and is a significant advancement in bulk emulsion technology. Reliable and easy-to-use bulk delivery equipment has been designed and developed to allow bulk emulsions to be used in a wide variety of shaft and tunneling applications.

Jan 1, 1987

By K. Oraee

Rate of penetration of Tunnel Boring Machines (TBM) has a significant role in the planning, measurement of productivity and performance of any tunneling project. In this paper, the application of Adaptive Neuro Fuzzy Inference System (ANFIS) in prediction of TBM penetration rate is evaluated. For this purpose, a database including Rock Quality Designation (RQD), Uni-axial Compressive Strength (UCS) of the rock, the Distance between Planes of Weakness (DPW) in the rock mass, and empirical data regarding rate of penetration of TBM from several tunneling projects are collected. The Rate of Penetration is then estimated by using ANFIS. These results are then compared with measured TBM penetration rates (actual data). It is concluded that ANFIS can be applied successfully for such purpose and result in high accuracy for prediction for the rate of penetration of TBM. The method provided in this paper can assist the mining engineer to estimate the performance of tunneling accurately.

Jan 1, 2012

By D. Royston

Gold ores containing antimony suffer from poor recoveries of gold in cyanidation due to the impact of antimony on the cyanidation process. Techniques such as lowering the pH for cyanidation can improve gold recovery, nevertheless a limit can be reached where high cyanide consumption makes traditional processing uneconomic. The paper outlines a process for the pre-treatment of gold-antimony concentrates to remove the antimony resulting in a low-antimony content gold-bearing residue suitable for efficient treatment for gold recovery through cyanidation. This hydrometallurgical process produces a by-product credit of commercial grade antimony trioxide as Senarmontite that can significantly offset the cost of the pre-treatment.

Jan 1, 2007