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By M. E. Rossi, V. Camacho

Reconciliation of production information is critical to evaluating the effectiveness of predictive models that would allow for the optimization of mining operations. Whether mining open pit or underground, mine-to-mill reconciliations can be one of management's better tools for the performance of proper accounting. Such reconciliations can also be a very useful tool in evaluation and optimization. This paper proposes a set of criteria and objectives for a typical reconciliation program. This paper also presents a stepwise, logical approach to performing reconciliations and discusses the benefits associated maintaining good information. It also highlights some of the potential pitfalls involved and the methods used to avoid collecting misleading information. These issues are illustrated with an example of a model-to-mine-to-mill reconciliation program that is being implemented at an operating mine. The program involves multiple predictive models (long-term and short-term block models), feed from three open pits and one underground mine, in addition to intermediate stockpiling, for a total of 23 mill streams. This paper presents a summarized version of this reconciliation program and its initial results as implemented at Minera Michilla S.A.

Jan 1, 2000

By James S. Hanson

Existing models proposed for the bacterial leaching of metal sulfides generally fail to predict solubilization rates at times greater than a few tens of hours. The reasons for this may be that these models are empirically based and use first order bacterial and chemical oxidation rates. This type of model is satisfactory for short time predictions (on the order of 20 hours) when the bacterially catalyzed dissolution is relatively minor. However, when bacterial action becomes more pronounced, these models consistently predict higher dissolution rates than those commonly observed in laboratory experiments. The present model uses several fundamental chemically and biologically based assumptions to predict the dissolution rate of a chalcopyrite concentrate for extended leach times up to the precipitation of jarosite. The main assumptions made are that Monod growth kinetics prevail, T. ferrooxidans adsorb onto the surface of the mineral (not necessarily mineral specific), and that during periods of high growth oxygen transport may become rate limiting. The model also relies on the energy efficiency of the bacteria in fixing carbon (growth yield) and correlates this value with available surface area of the mineral particles and the bacterial growth rate.

Jan 1, 1989

By Young C. Kim

Determination of the minimum sampling requirements of the run-of-mine (ROM) coal is very important for the purpose of meeting contract specifications. It is also important for the purpose of meeting emission regulations at a coal-burning power plant, such as the one located at Homer City, Pa. The classical statistical sampling theory can be applied to this problem, if ROM coal samples are known to be spatially (or serially) uncorrelated. On the other hand, the estimation variance concept from the Matherson's geostatistics must be used, if the samples are spatially correlated. Conditional simulation technique combined with simulation of the existing mining method is used to determine under which circumstances ROM coal samples do not preserve the spatial correlation. Only after establishing the degree of correlation that exists among ROM samples, an optimal sampling scheme can be devised using either the classical statistics Or the geostatistics. The minimum required sample volume can then be calculated using the well-known Gy's formula. This paper describes the results of the above investigation using the Helen coal mine data of the Homer City Owners. Empirical guidelines for determining the degree of correlation are also provided for coal mine operators.

Jan 1, 1986

By Henri Letient, Tom Aley, David Evans

Antamina is a large open-pit copper and zinc mine located within the Central Andes of Northern Peru at an altitude of 4300 masl. The facilities are situated within the headwaters of several watersheds, within the Amazon basin. Nearby villages rely heavily on springs and streams for drinking and irrigation water. The principle source of baseflow during the dry season is from Cretaceous karstic limestone aquifers. Antamina will produce nearly 1.4 billion tonnes of waste rock over its mine life. Finding suitable sites for storing large volumes of waste rock is often a challenging task – especially in karstic, alpine terrain. Detailed hydrogeological investigations are essential for delineating the karstic hydrogeologic watersheds associated with the proposed waste facilities, which are often very different than topographic (hydrologic) watersheds. Contamination vulnerability mapping at Antamina consisted of geological and karst mapping, geophysical surveys, geochemical testing, dye-tracer studies, drilling and aquifer testing. Detailed mapping followed by dye-tracer studies proved to be the most cost-effective methods for characterizing the karst aquifer systems. The results were used to optimize waste rock management at the site to minimize potential impacts on groundwater resources.

Jan 1, 2005

By W. Ter-Minassian

Besides the question of the stability of the roof and walls, one of the main problems encountered with tunnelling and shaft-sinking through the soft ground of alluvial origin forming the sub-grade of most large towns is settlement. Public transport and road tunnels in town centres are particularly affected, as they cannot generally be designed at any great depth for several reasons, such as the fact that ventilation shafts and access to the surface by means of stairs, escalators, lifts, ramps and so on must be fitted into the limited space available and are therefore costly, and because of the difficulties of driving below the water table. It is for this reason, coupled with the need for wide radius curves, that tunnels now so often pass close under buildings and monuments which must not be exposed to any risk of damage from subsidence during excavation. Grouting is the usual method used for consolidating soils, improving their strength and making them less compressible, but it is itself liable to cause heaving and cracks in the buildings above and has many other attendant dangers, including continually revised estimates which are the reason for the often inordinately high costs met with in urban tunnelling to-day. The mechanics of the problem have been studied and it has been found that a fraction of the total settlement is

Jan 1, 1997

By N. Colvin, J. W. Gulyas

HISTORY The Surigao Nickel Refinery of Marinduque Mining and Industrial Corporation is located on Nonoc Island off the northwestern coast of Mindanao in the Philippines. Nonoc Island is part of the Surigao Mineral Reservation which had been identified as early as 1912. Initial interest in these deposits was due to their iron content, and their value as a nickel deposit was not seriously entertained until the late 1950's. The Philippine government undertook extensive test pitting and sampling programmes at that time and in the early sixties Marinduque became involved in helping to establish firmer ore reserves. Evaluations of the test pitting programme indicated reserves of 75,000,000 tonnes of ore averaging 1.22% Ni, 0.1% Co and 38.5% Fe. The Philippine government called for bids on the reservation in 1962 and Marinduque and Sherritt Gordon carried out some feasibility studies for the recovery of nickel from the deposit. However, it was not until 1968 that Marinduque was granted proper authority to exploit the Surigao deposits. Marinduque and Sherritt then entered into an agreement which allowed Marinduque to utilize a process developed by Sherritt for treating lateritic ores. During 1968, a 25 st/d pilot plant was erected in Fort Saskatchewan, Alberta for the purpose of modelling all process steps. A 10,000 tonne ore sample was sent from Nonoc as feed stock for the pilot plant.

Jan 1, 1979

By Kostas Fytas

A computer package has been developed which is capable of evaluating alternative production schedules (long and short range) of an open pit mine once the ultimate pit limits have been defined. The model user can choose the best alternative according to cash flow considerations and the particular mining conditions. The package involves a combination of simulation for long range production scheduling and linear programming for short range scheduling. The simulation model based on an iterative technique, maximizes the profits within each long scheduling period (eg. year or sixth month period), and at the same time defers stripping as long as possible. A minimum exposed ore quantity is kept at the beginning of each mining period. The final long range schedule satisfies a set of constraints for each period, mainly ore quality and quantity constraints for ore and waste. An interactive smoothing procedure at the end of each period results in a schedule that is feasible in terms of mining practice. Finally a cash flow analysis model carries out cash flow calculations so that the user can select the best alternative. The linear programming model, based on a certain number of shovel regions, defined interactively by the model user, calculates the optimum production schedule for each short period under consideration, so that a set of constraints is satisfied.

Jan 1, 1986

By Stéphane Servant, Jacques Ouellet, Ferri Hassani

This paper presents essentially the logistic and practical aspects involved for in situ testing of mine paste backfill with a self-boring pressuremeter. The investigation discussed in this paper is part of an extensive and ongoing research project to identify and validate an in situ testing technique for cemented mine backfill such as hydraulic or paste backfill as well as Insitu behavior of backfilled stopes. After a literature review on field testing of soils and past experiments on mine backfill in situ testing, the self-boring pressuremeter was selected as the most appropriate instrument for this task. The authors presents in this paper the technical aspect involved in a field trials that was conducted in a Canadian underground mine using paste backfill. The results of this first successful trials show that self-boring pressuremeter test can provide high quality and reliable backfill characteristics results, using analytical techniques developed for soils (Ouellet et al., 1998). The parameters obtained were: estimation of the lateral stress in the ground, the soil stress-strain response and the soil strength. The logistic and equipment required to conduct such testing underground is fully described. Performance achieved in the field and technical difficulties encountered are highlighted. Recommendations for future experiments with such instruments are given. Some potential technical improvements to better adapt this in situ testing technique to mine backfill are proposed.

Jan 1, 2001

By Ronald E. Yarbrough

As a result of concern for the citizens of the State of Illinois who owned structures above underground mine workings, the Illinois State Legislature passed House Bill 158 in 1978. This bill amends the Illinois lnsurance Code and creates the Mine Subsidence Reinsurance Fund which is an insurance pool that is to receive a state appropriation of $500,000 as "start-up" money. One hundred thousand dollars has been paid to the fund as of October, 1982. The Fund is to return this appropriation to the State and is to remain self-supporting from premiums. The Fund utilized a pre-existing institution, which also was an insurance pool, the "Fair Plan Facility" and its governing Board, consisting primarily of insurance executives, to administer the program. The Mine Subsidence lnsurance Act went into effect October 1, 1979, and the bill provides that property owners in the State of Illinois may purchase up to $50,000 of mine subsidence insurance which is attached to their fire insurance policy. The deductible is normally 2%, but cannot be less than $250 or more than $500. The annual rate structure for residential structures in 1981 for $50,000 coverage is $10 (frame), and $12 (masonry). The rate structure for commercial buildings is based on the value of the building and the rates for $50,000 maximum coverage is adjusted upward. The insurance was mandated by the State Department of lnsurance and rolled onto the insurance policies of the homeowners in 34 counties which had been recognized as having sufficient exposure to subsidence damage to be covered by the Act. One percent or more of the land surface is undermined in each of the 34 counties. In the other counties undermined in the State of Illinois, insurance is available to the homeowner upon request to the private insurance carrier.

Jan 1, 1982

By Daryl L. Gusey, John T. Neubert, Matthew A. Sares

The Colorado Geological Survey completed an inventory of environmental degradation associated with abandoned and inactive mines on National Forest System lands in Colorado. In the course of the inventory, areas with naturally occurring acid rock drainage were also noted. Approximately 18,000 abandoned mine- related features were inventoried, including about 900 features that are considered significant enough environmental problems to warrant further investigation. Water quality data, such as pH and conductivity were gathered at all features where water was present, such as draining adits, seepage at the toe of dumps and tailings, and standing water in shafts. Samples were taken where field tests indicated low pH andlor high conductivity, including several areas with naturally occurring acid rock drainage. Samples were analyzed for dissolved and total metals, and for selected anions. All mine locations and data collected by the field geologists were entered on field forms and, subsequently, into a computer database and GIS format. With the information provided by the inventory, the Forest Service, in cooperation with other agencies, has been able to prioritize abandoned mines for reclamation. In most cases, cleanup is approached on a watershed basis. Mines in priority watersheds have been selected for reclamation first. Watersheds where studies prerequisite to cleanup are occurring include the upper Anirnas River, Willow Creek (tributary to the upper Rio Grande), Chalk Creek (tributary to the upper Arkansas River), the Uncompahgre River, and the Alamosa River. During the inventory, evidence of naturally occurring water quality degradation was found in areas where little or no evidence of mining activity exists. These areas include the upper Alamosa River, the Middle Fork of Mineral Creek, Peekaboo Gulch, and Handcart Gulch. Water from these natural sources has been found to significantly exceed Colorado water quality standards for several metals.

Jan 1, 2000

By John Mastoris, Kostis Dragasakis, Kostas Kouklidis, Shkurtë Gashi, Halil Berisha, Jenuz Bulica

Titan Group’s environmental policy and Sharrcem’s Corporate Social Responsibility (CSR) are the driving forces behind the development and implementation of a comprehensive Rehabilitation Plan at Dimce Quarry, which is the main raw material source for Sharrcem Cement Plant since the 1970’s, located in the municipality of Hani i Elezit in Kosovo. Based on an Environmental Impact Assessment Study and the approved Mining Plan and also on the principles prescribed in the Guidelines on Quarry Rehabilitation, released by the Cement Sustainability Initiative of the World Business Council for Sustainable Development (WBCSD-CSI), Sharrcem has adopted a quarry operation and rehabilitation process in line with the best practices in the mining and cement sector. This paper discusses the background for the development of the rehabilitation plan and the results of rehabilitation activities, as have been implemented over the last few years. The main objective of the progressive rehabilitation plan at Dimce Quarry is to restore the depleted pit and return it back to the original land owners for resettlement. To date approx. 3,4Ha of former mining area has been restored by backfilling and levelling of the depleted closed pit and returned back to owners, who have built their houses and turned it into a living area again. This Quarry has turned out to be a real composition and practical example of preserving and returning back the natural resources in a state compatible with the surrounding environment and with respect to the needs of the local stakeholders. The motivation for business to engage in rehabilitation activities in the first place lies in the belief that the development and implementation of a progressive and practical Quarry rehabilitation plan and restitution of the land will deliver significant environmental and social benefits that outweigh the long-term rehabilitation costs, while maintaining the company’s reputation.

Jan 1, 2017

By G. Brofas

Mt Giona situated in the floristic hot-spot of southern-central Greece has an especially rich flora that counts more than 1000 native vascular plant taxa (species and subspecies) and an important plant endemism that is estimated to be about 10% of the native flora. The danger of population reduction of rare and endemic plant species and the opportunity to use rare native species in rehabilitation projects are two different aspects of rehabilitation planning in Mt Giona. In this study, an inventory of rare and endemic species of the area, their classification into IUCN threatened categories and an estimation of their habitats vulnerability are provided. The results emphasize the necessity to develop a monitoring program to analyze population viability of certain threatened plant species. The creation of artificial micro-reserves on calcareous spoils derived from bauxite mining for the conservation of water-stress tolerant rare and endemic plants is also proposed. An inventory of the species that have colonized the mining spoils was also undertaken. Twelve of them are endemics. Seven native species, because of their biological and ecological features, were selected for rehabilitation purposes of disturbed areas by mining activities. Seed germination, aspects of their reproductive biology and seedling emergence after sowing in pots under field conditions were studied. The seed germination study in the laboratory led to the identification of the optimum germination conditions and the creation of germination protocol for each species. Seedling emergence depends on the sowing season and the mulching. The use of the above species is recommended for rehabilitation purposes. The creation of artificial micro-reserves on calcareous spoils derived from bauxite mining for the conservation of water-stress tolerant rare and endemic plants is also proposed.

Jan 1, 2007

This paper reviews the technical advice available to support companies in the delivery of social aspects of sustainable development. It will draw on diverse experience from the sparsely populated plains of the Central African Republic, one of the poorest countries in the world, to the densely populated villages of the Carpathian Mountains in Slovakia. It will review basic requirements for the consideration of social issues, as well as guidance on international best practice. It will review: the legal basis; coverage; consideration of alternatives; scope; inclusive decision-making; indicator development; impact monitoring and evaluation. The paper will discuss the breadth and depth of social issues for consideration, including the realms of responsibility of a company in terms of social development in different operating environments. The extractive industries invest substantial amounts of money which typically dwarfs local development, health or education budgets. Capacity building for local authorities is not directly the role of the company, but when understood as a strategy for risk management, it can play a vital part of sustainable development that benefits the local community and reduces the risk of social problems impacting profits. The paper will argue that social impact assessment is most effective when the outcomes are in line with a company?s principles and support core business practices. It is important that social impact assessment is viewed as an integral part of project decision-making and moves away from mistrusted PR and unsustainable philanthropy toward partnership, which finds suitable and appropriate solutions delivering ?win-win? outcomes. While development should not be seen as a direct company objective, engaging with development actors to better understand the operating context can ensure that social investment complements existing initiatives. The paper will also present different mechanisms for engaging with local actors, as well as developing successful social programmes.

Jan 1, 2007

By T. H. Udayashankara

Soil pollution, a very serious environmental problem, has been attracting considerable attention in recent years. It is now generally recognized that land as a component of the environment deserves the same attention and protection as water and air. This recognition has arisen perhaps because of increased incidents of land pollution, the scarcity of land, and increased awareness and concern about long-term effects of land pollution on terrestrial and aquatic eco-systems and on ground water quality. Contamination of land results from a wide range of human activities, including industrial discharge process, disposal of wastewater and agriculture. The environmental impact of exploration, production and refining of crude oil is a major concern in developed and developing countries. Because of the known adverse effects of petroleum hydrocarbons on soil ecology and fertility there has been growing interest in the development of efficient technologies for the remediation of contaminated land, with a view toward making it available for further use. Crude oil is a natural product and as such is susceptible to degradation by naturally occurring micro flora. Bioremediation has become an important method for the restoration of oil-polluted environments. A bench scale study was conducted to evaluate the bioremediation technique in treating soil contaminated with transformer oil. The steps involved in this study are: (1) Preparation of contaminated soil, (2) Extraction of PAHs and PCBs from contaminated soil, (3) Treatment of contaminated soil in slurry batch reactor, and (4) Analysis of PAHs and PCBs by gas chromatography technique. The performance of reactor was assessed by measuring parameters like COD, PAHs and PCBs. The study was con-ducted for six different pulp densities ranging from 20% to 40%. The maximum removal of PAHs and PCBs was observed for 20% pulp density.

Jan 1, 2008

By Frank W. Bowdish

During the early 1960's, a method was developed for refining sand from the Arkansas River to produce a feldspathic product that was proposed for use in making colorless glass. Because of the need for chemical uniformity, a cooperating glass manufacturer specified certain ranges of percentages for each chemical constituent of the sand. These specifications were met by fulfilling the single requirement that alumina vary by no more than 20.1 percent from the specified value. This translated to a total variation of only about 1 percent in the feldspar content of the mixed quartz-feldspar products. Because the feldspar was lighter than the quartz, the average density of refined sand varied depending on composition. Densities, determined to five significant figures, of several samples were correlated with their chemical analyses, and the correlation could then be used with density determinations to more reliably indicate compositions than by chemical analyses only. The effects of several variables on the composition of refined sands were studied. There was a regular variation in the proportion of feldspar with screen size. A series of samples with their natural size distributions were more nearly uniform in composition than the same sands after screening and recombination. The screening and recombination process was done so that the sands had identical size distributions. Variations in the refining showed little effect on composition. A pile of flow-back sand from a construction sand washer was found to be severely segregated. However, samples taken from many points in the river near the sand plant and from the flow-back discharge pipe over several weeks very nearly met the uniformity specification. If care was taken to avoid segregation either before or during processing, it should be possible to meet the uniformity specifications for a feldspathic glass sand.

Jan 1, 1978

By C. L. Karr, E. J. Gentry

Researchers at the U. S. Bureau of Mines have developed a control algorithm to efficiently manipulate chaotic systems. The control, based on both fuzzy logic and genetic algorithms, prescribes actions that drive the chaotic system to acceptable regions of state space. The use of fuzzy logic enables a person who has limited experience with a chaotic system to establish a set of rules for manipulating the problem environment, and a set of membership functions that define terms used in the rule-set. Genetic algorithms are search algorithms based on natural genetics, and are used in the control algorithm to select membership functions that provide for a suitable level of control. The Bureau-developed algorithm controls the computer simulation of a ball bouncing on an oscillating table, a system that exhibits chaotic behavior.

Jan 1, 1993

By Ishwar G. Mulani

In conveyor design, the first step is capacity and the second step is belt width and speed. The third step is decision on 'ff," where distinction arises between DIN/ISO and CEMA for calculating resistances. Then again, both the methods are virtually similar. This topic helps in understanding Dm design style and its comparison to CEMA. This topic is from the book Engineering Science and Application Design for Belt Conveyor wherein the issue has been analysed in detail. It presents a workable calculation model to calculate the value off in design office, based on conveyor parameters. CEMA uses Kx, Ky and 0.01 5 instead off. Thus, f is a sum effect of Kx, Ky and 0.015. Hence, knowledge on f is also applicable to Kx and Ky. This helps to understand their relationship.

Jan 1, 2004

By R. L. Shaw, D. W. Alexander

Consolidation Coal Company's Loveridge Mine operates the only coarse coal hoisting and overland slurry transport system in North America. The system has been in operation since April 1980 and according to current haulage levels will have handled over two million tons by this conference date. Original performance goals have been exceeded. The systems will be described and their application to rapid excavation and tunneling haulage needs will be discussed. Manuscript not received in time for publication.

Jan 1, 1983

By David J. Leeds

Increased interest in the utilization of the underground environment for water conveyance tunnels, vehicular tunnels, room and pillar type storage chambers, and military installations has focused attention on the possible effects of seismic activity on the stability of these types of structures. Earthquake experience has generally been related to the seismic stability on the surface of the earth. To establish aseismic design criteria, we attempt to predict the seismic exposure of a given site, both in terms of the spectrum of motion to which the structure must react favorably, and the recurrence rate of that motion. Experience gained from studying the effects of the Plowshare underground nuclear tests on existing tunnels and mines, coupled with the experience of the behavior of tunnels and mines in earthquake regions, provides us with an insight to predict the possible effects of earthquakes on underground openings and to establish design criteria. The type of damage ranges from minor fracturing and movements along pre-existing joints or faults through deformation of openings to collapse. The methods used to establish the seismic design criteria for an underground opening require modification of surface criteria to account for the difference in both amplitude and spectra underground. An aseismic evaluation should be performed on all important projects in areas exposed to possible earthquake motion. To perform this evaluation, information is required pertaining to the geometry and properties of structure and ground. Dynamic as well as static properties are required. A prediction of performance can be derived by exposing a model of the site, expressed in terms of its properties and geometry, to a design earthquake.

Jan 1, 1997

By S. Orr

Flow in heaps and dumps is a two-phase flow phenomenon, though for many applications it could be simplified as unsaturated flow. Unlike saturated flow (typical of ground water flow), where permeability is independent of other hydraulic parameters, unsaturated flow permeability depends on the degree of saturation and/or on capillary pressure. Several recent field studies suggest that flows in heaps and dumps tend to concentrate in preferred pathways, bypassing much of the ore. Different preferential flow phenomena are triggered, promoted and influenced by different heap structures, by pretreatment, by the composition of the leach solution and by application rates and schedules. The structure of heaps and dumps is determined and affected by every stage of their construction -from blasting to crushing to conveying and stacking of the material. History of heap construction and operation combined with monitoring, mapping and certain field tests can reveal patterns of flow and transport in a given heap and can shed light on the physical mechanisms behind it. Such insight can provide a first cut on heap leaching enhancement by either eliminating or bypassing physical barriers to flow and leaching. Based on the understanding of the heap structure, advanced flow and transport models can be constructed and further enhance the insight. This insight is essential for understanding cause and effect and can provide a basis for decision making. Further, based on the physically-based models, an intelligent control agent, such as MRDS1, can learn and build a self-learning representation (or a model) of the complex heap leaching system, followed by dynamic optimization and planning of heap leaching and heap rinsing.

Jan 1, 2003