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By C. Birch

"The purpose of this study was to establish the impact of discount rates on cut-off grades for narrow tabular gold deposits as characterized by the goldfields of the Witwatersrand Basin in South Africa. There are various methods available for determining the cut-off grade, from simple breakeven calculations to sophisticated software packages that consider a variety of inputs to optimize the cut-off grade. For this study a simple financial model was created in Microsoft Excel® that links the ore flow, block listing, and the cash flow. This allows the cut-off grade to be optimized considering how the cost of capital and chosen discount rate affect the cash flow.The discounted cash flow (DCF) and resultant net present value (NPV) are a widely used valuation method for production properties according to the South African Code for the Reporting of Mineral Asset Valuation (SAMVAL Code). The financial model in this study utilizes the Solver function, as well as simple Microsoft Excel spreadsheet formulae to optimize the NPV. Solver was chosen as it is a standard feature in Excel and thus no additional software costs are incurred beyond the basic Microsoft Office suite. For the purpose of this study, just narrow tabular gold deposits of the Witwatersrand Basin were considered. An example of a typical ore block listing, as well as the costing figures, was obtained from an operating gold mine. The results obtained from the study financial model were compared to the current cut-off grades obtained from the mine using their proprietary optimizer program, and were found to be comparable. The methodology utilized for this study thus appears valid.The cut-off grade was optimized considering the cash flow, which includes the variable mineral resource royalty tax, the variable gold income tax, as well as the discount rate. By comparing the resultant NPVs using discount rates of zero, 9%, and 12%, the impact of the discount rate on cut-off grades, resultant life of mine, and average mining grades (AMG) could be compared for the example ore block listing. The South African Code for Reporting of Exploration Results, Mineral Resources and Mineral Reserves (SAMREC Code) does not require operations to state if a discount rate was considered in determining mineable reserves. Mining companies approach the question of applying discount rates in determining their cut-off grades, and thus mine planning strategy, in different ways. Due to the negative impact that optimizing purely on NPV has on the life of mine, some choose to optimize only on profit. Other companies have reverted to utilizing pay limits as their primary grade planning strategy. The calculated cut-off grade is then considered to be another planning indicator rather than a hard determination of mineable reserves."

Jan 1, 2016

By Kourosh Shahriar, Kazem Oraee, Ezzeddin Bakhtavar

"In this paper, a relationship between dependant parameters and the crown pillar thickness is first introduced. This relationship defines geotechnical problems caused by thin pillars and economic considerations created by pillars that are thicker than the optimum size. For this purpose, a dimensional analysis as an effective physico-mathematical tool was used. This technique restructures the original dimensional variables of a problem into a set of dimensionless products using the constraints imposed upon them by their dimensions. A model is hence introduced that calculates the optimum pillar thickness. The relationship introduced here and the method applied can be used by mining engineers in all situations where a combined open-pit and block caving method is deemed to be the most appropriate mining method.INTRODUCTIONMany deposits can be mined entirely with the open-pit method; others must be worked underground from the very beginning. In addition, there are the near-surface deposits with considerable vertical extent. Although they are initially exploited by the open pit method, there is often a ""transition depth"" where decision has to be made about changing to underground methods.Some of the biggest open-pit mines worldwide will reach their final pit limits in the next 10 to 15 years. Furthermore, there are many mines planning to change from open-pit to underground mining due to increasing extraction depths and environmental requirements. In this way, it is likely that block and/or panel caving will enable the operations to continue achieving a high production rate at low costs as an underground method (Bakhtavar et al., 2009).In these cases, it is often necessary to consider a crown pillar beneath the transition depth (open-pit floor) before starting an underground caving stope method (Figure 1).There are generally two kinds of crown pillar: a ""surface crown pillar"" and ""crown pillar between open-pit and underground mining."" In general, they both play the similar role in mining. Since the primary purpose of a surface crown pillar is to protect surface land users, the mine, and those working in it from inflows of water, soil, and rock; it is vital that the surface crown pillars remain stable throughout their life. When a crown pillar could potentially remain between open-pit and underground mining it is specially proposed to prevent water entering from the open-pit floor into the stope, as well as to reduce open-pit wall and floor caving."

Jan 1, 2010

By A Horne, Z Graszkiewicz, D Dettrick, R Evan, B Neal

"Most of VictoriaÆs rivers and aquifers are already fully allocated or reaching full allocation. In regions without a well-established water market, access to water entitlements to facilitate new development is limited. In areas with established water markets, mine developers face an undue cost burden in circumstances where they are only planning to consume a fraction of the water entitlements that they purchase. The challenge for water managers is to ensure protection of water resources and other water users without creating an unnecessary disincentive for those types of developments that return most of the water that they take from water sources. The opportunity for development of a mine is explicitly linked to a particular location and must be developed where a resource is located or it cannot be exploited at all. Regulatory arrangements that facilitate development may have a positive impact on economic development, particularly where water availability is a potentially limiting factor. Net volume licensing has the potential to allow increased economic outcomes through improved licensing of access to water. Net volume licensing differs from traditional water licensing in that it authorises access to water on the basis of ænet useÆ rather than æthe gross volume takenÆ. This paper asks under what conditions net volume licensing is likely to be feasible and effective. In particular, the paper examines the information and accuracy requirements to allow net volume licensing decisions to be made. This work is based around five case studies in Victoria that were used to examine the potential for net volume licensing for mines and quarries. Assessing a potential net volume licensing arrangement requires the regulating authority to have an understanding of the inputs and outputs of water to a site. In contrast, assessment of take and use licences consider only a single input. It was concluded that the conditions that lend themselves to net volume licensing include: well understood water inputs and outputs, including appropriate accuracy of information where the location of site water inputs and outputs are the same where the timing of extraction and discharge can be managed to minimise impact on the water resource.A key remaining challenge is establishing an accounting framework that allows net volume licensing under current water resource limits. CITATION:Graszkiewicz, Z, Horne, A, Neal, B, Evan, R and Dettrick, D, 2013. The practicalities of implementing net volume licensing of water use in mines and quarries - a discussion based on Victorian case studies, in Proceedings Water in Mining 2013, pp 241-250 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 26, 2013

By F Cappuccitti

A colourimetric technique, originally developed for methyl iso butyl carbinol (MIBC) based on the Komarowsky reaction, has been extended to a wide range of common mineral flotation frothers. The procedure, which is briefly described, is shown suited to on-site determinations in a campaign at Kennecott Utah Copper Copperton Concentrator (Rio Tinto). Some observations are described, including: frother (MIBC) concentration evolution down a bank, frother distribution between pulp and froth phases, and loss of frother over time due to adsorption on certain minerals. A possible interference with a fuel oil addition was overcome. MIBC in recycle water was also measured. The ability to monitor frother easily will help interpret gas dispersion behaviour and should permit further optimisation of flotation cell hydrodynamics and chemistry. The capability to directly measure should help optimise the type, amount and location of frother addition, and to assess frother recycled with reclaim process water.

Jan 1, 2005

By W. E. Robinson

Oil-shale kerogen was processed into oil and oil products before the first oil well was completed by Drake in 1859. However, because of economic and other advantages, natural petroleum has been the principal source of liquid fuels and lubricants since 1859 and is a convenient root of many [organic] chemicals in common use today. In recent years the difference has narrowed between the cost of producing liquid fuels from well petroleum and other sources. This narrowing of cost difference has resulted both from the increased cost of finding new sources of petroleum in the United States and the experimental demonstration of lowered costs for synthetic liquid fuels by the Federal Bureau of Mines and by industry. Available petroleum resources of this country are being reduced and eventually may be inadequate to meet the demand. Alternate means of assuring an adequate supply of liquid fuels for this country include the development of processes for utilizing other carbonaceous materials such as oil shale and coal.

Jan 1, 1960

By W. M. G. Heeley

In the province of Alberta the coal measures dip at so many different angles, between the horizontal and the vertical, that many different systems of haulage are in use. I will, however, only touch briefly upon the general -systems in use, and devote the major portion of this paper to a discussion of endless-rope haulage and its adaptibility to various conditions in coal mines; dealing in particular with the endless-rope haulage that was installed at Brule during the month of August 1923. In coal seams that are approximately level, and newly opened, hand-putting or tramming from the face is the cheapest, but when the mine is further developed tramming is out of the question, and the use of ponies is the next consideration. The time arrives, however, when mining reaches a point where the economical haulage of coal by horses cannot be done profitably, and then some system of mechanical haulage must be installed. The installation of any system should be carefully considered before any particular type of haulage is adopted, because a great deal depends upon the grade or dip of the seam. Motor haulage is impossible to operate profitably on a grade of over 6 per cent and, while it is possible to use ponies, on short runs, up to 9 per cent, some other means of main and secondary haulage must be installed when a 9 per cent grade, is exceeded. I will, therefore, deal first with secondary haulage, because even though a main haulage is established, secondary haulage can be used to feed the main haulage.

Jan 1, 1925

By Sergio Romo, Gerardo Fuentes, Adriana Garcés

Refractory ores with gold entrapped in a sulfide matrix, must be processed in a first stage with chemical or physical treatment in order to liberate the gold for a subsequent step with cyanide. The goal of this research was to compare the refractory behavior of a gold concentrate treated using two pretreatment methods: pressure oxidation and fine grinding. Gold concentrate from Viacha Mining in Bolivia, assaying 50.11 gpt, with a P80 of 131 ?m was used. The concentrate contains arsenopyrite and pyrite as main sulphides in the matrix. A preliminary test with cyanide resulted only 13.5% of gold extraction with 4 hours of stirred leaching. Using an autoclave oxidation with sulphuric acid and 12 bar oxygen pressure at 220°C pretreatment, the cyanide gold extraction increased to 69.0% in 4 hours. When material was ground in a pulverizer, producing a P80 of 20 ?m and the product directly cyanided, stirred leaching gave a gold extraction of 65% in 4 hours. For both techniques, the effect of temperature, sulfur produced in autoclave oxidation, optimization of the cyanide and the nature of residues were also studied.

Jan 1, 2014

By D. G. Almond

Nkomati Nickel Mine in South Africa processes one of the world?s hardest ores in a 375k TPM autogenous grinding circuit. The plant employs an unconventional processing circuit, comprising a primary autogenous mill (AG or FAG) and pebble crushing circuit followed by a secondary hybrid pebble/ball mill and classification cyclone cluster. Advanced Process Control (APC) or Expert Control is now generally accepted as an advantage in most modern high capacity concentrator grinding circuits. This paper reviews the installation of model predictive control at Nkomati and examines the results and benefits of installation in an autogenous mill during plant ramp-up. The paper also demonstrates how predefining process control objectives together with good plant and supplier cooperation can achieve a robust and reliable APC implementation on a very short site program. The results conclusively demonstrate operational and economic benefits during circuit operation with the advanced process control system ON. Production performance and circuit stability were significantly better than during manual control.

Jan 1, 2012

By Pratt Rogers, Aaron Young

Digital transformation (DT) is the process by which entities adapt themselves to modern technology. As digital technology becomes more prevalent (automation, cameras, sensors, touchscreens, artificial intelligence, etc.), there will be increased pressure on companies to leverage it for additional gains. For many companies in the mining industry, this will involve overcoming a steep learning curve. Furthermore, as the long-term success of the mining industry is dependent on a labor force with new skills (data management, analytics, digital literacy, etc.), new curriculum will need to be appended to the mining engineering discipline. This paper considers the mining industry’s need for DT. Then, it presents a three-part review of the foundational components of the DT process–ubiquitous data, connectivity, and decision making. Finally, it provides a discussion on the future of DT in mining as well as a research direction, which identifies the need of academia to provide support for mining companies in the form of both research and the education of digitally literate, dynamically capable mining engineers into the coming decades.

By J. Trojacek

A large-scale development in exploration and production of uranium ores in the Czech Republic was done in the 2nd half of the 20th century. Many uranium deposits were discovered in the territory of the Czech Republic. Over a period of 50 years approximately, 110 000 tons of uranium in concentrate were produced. Different mining methods were developed and used. One of the most considerable deposits in the Czech Republic is the site Hamr na Jezere ? Straz pod Ralskem where both mining methods ? the underground mining and the acidic in-situ leaching ? were used. The extensive production of uranium led to widespread environmental impacts and contamination of groundwaters. Over the period of ?chemical? leaching of uranium (ca. 32 years), a total of more than 4 million tons of sulphuric acid and other chemicals have been injected into the ground. Most of the products (approximately 99.5 %) of the acids reactions with the rocks are located in the Cenomanian aquifer. The contamination of Cenomanian aquifer covers an area larger than 27 km2. The influenced volume of groundwater is more than 380 million m3. The total amount of dissolved SO4 2- is about 3.6 million tons. Approximately 0.5 % of the contamination is located in the Turonian aquifer. After 1990, a large-scale environmental program was established and the Czech government decided to liquidate the ISL Mine and start the remediation in 1996. The remediation consists of contaminated groundwater pumping, removing of the contaminants and discharging or reinjection of treated water. The objectives of the remedial activities are the followings : to restore the aquifer to a condition guaranteeing continuing usability of Turonian water of Northern Bohemia Cretaceous, to decommission boreholes and surface installations and to incorporate the surface of leaching fields into the ecosystems taking into account regional systems of ecological stability and urban plans. Nowadays four main remedial technological installations for reaching of these aims are used - the ?Station for Acid Solutions Liquidation No. One?, the ?Mother liquor reprocessing? station, the ?Neutralization and Decontamination Station NDS 6? and the ?Neutralization and Decontamination Station NDS 10?. Total capacity of this complex is sufficient to reach the target values of remedial parameters in 2037. The remediation action consists of: pumping of residual solution to the surface, separating uranium from the solution and reprocessing contaminants into commercially usable or ecologically storable products. It is expected that the amount of withdrawn contaminants will vary from 80 000 to 120 000 tons per year. Total costs of all remediation activities are expected to be in excess of 1.5 billion EUR.

Aug 1, 2013

By William Nicoll

Those who use electric detonators in firing blasts will be interested in a new electrical testing instrument known as the ‘Blasters’ Friend’, recently devised by the New York Blasting Supply Co. of New York. Owing to the necessarily delicate construction of the platinum wire bridge in the shell of a detonator, it frequently happens that it becomes broken or disconnected; thus destroying the circuit and rendering the detonator worthless. In many cases, misfires and premature explosions are caused by defective detonators. Heretofore, to detect the deficiencies of a detonator before using has been an impossibility, owing to the absence of a testing instrument adapted to the purpose.

Jan 1, 2010

By S. Eck

In previous work the influence of the casting speed on the flow field and the shape of the solidification front in an industrial 0.82 x 0.25 x 0.8 m³ bronze caster had been investigated. Both numerical and experimental model represented 1:1 the real caster geometry. A comparison of the results of both numerical and experimental models for the flow during the casting process showed a good agreement in the qualitative velocity fields (flow direction and vortex formation). This work represents a parameter study of the numerical model with variations of the turbulence conditions at the inlet in order to clarify their influence on the flow field in the caster. In order to find the best boundary condition at the inlet, the numerical calculations for water have been compared with the measured flow fields in the water model. The new boundary conditions were then applied to the numerical model of the bronze casting process.

Jan 1, 2009

By R Dimitrakopoulos, R Goodfellow

One of the primary objectives when optimising a mining complex is to maximise its value for the primary stakeholders. In order to achieve this objective, it is necessary to holistically optimise all aspects of the mining complex, including decisions of when to extract materials from the available sources, how to blend or stockpile these materials and how to best use the available processing streams to satisfy customer demand. Existing methods for global, or holistic, optimisation ignore the compounded effects that risk has on the performance of a mining complex. Over the past decade, several stochastic optimisation approaches have been proposed to integrate various forms of uncertainty into the open pit mine design and production scheduling. These methods, however, are limited in their ability to simultaneously optimise the production schedules for the portfolio of mines, material destination policies, the use of the available processing streams and the various products that are produced at each location of the mining complex.This paper aims to discuss a new method for the global optimisation of open pit mining complexes with geological uncertainty. The proposed generalised methodology is capable of modelling and holistically optimising mining complexes, including aspects related to production scheduling, blending, stockpiling and non-linear interactions that often occur in practice, but are over-simplified in existing models. Two case studies are discussed to highlight the need for these complex, stochastic optimisers. First, a case study for a nickel laterite blending operation highlights the need to integrate geological uncertainty into the optimisation in order to ensure product quality constraints are respected. Second, a case study for a copper-gold mining complex highlights the added value when simultaneously optimising the production schedule and the stockpiling and treatment of extracted materials.CITATION:Goodfellow, R and Dimitrakopoulos, R, 2014. Stochastic optimisation of mineral value chains – developments and applications for the global optimisation of mining complexes with uncertainty, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 13–22 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By Michael S. Miller

In 1984, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied the 34,050-acre Cow Creek Wilderness Study Area (WSA) in order to evaluate its mineral resources. The WSA, located about 60 miles southeast of Havre, MT, contains sandstones, shales, clays, and coal of Cretaceous age. The Cretaceous rocks have been intruded by ultramafic diatremes. Quaternary glacial, stream, and landslide deposits overlie the older rocks. Claims are staked at five of seven sites favorable for diamonds within the WSA and at additional sites nearby. Although the ultramafic diatremes within and near the WSA contain minerals that are indicators for diamonds, no positive evidence of diamonds was found during this study. An abandoned coal mine, the Shellenberger, is inside the southwest boundary of the WSA. Possible petroleum and natural gas at depth are currently of interest; land within the WSA is leased or under lease application for oil and gas. The WSA contains subeconomic clays, zeolites, gold, silver, platinum group metals, and coal.

Jan 1, 1986

By DV Boger

Rheology is the science which deals with the deformation and flow of matter. Thus nccology is concerned with the flow of any material. The mining industry is concerned with digging things out of the ground, extracting the good stuff and throwing away the had stuff. In the upgrading processes associated with mining, is mineral processing, wet techniques are used where the primary material being handled is a particulate fluid, ie a suspension. After the processing operation, with the concentrates extracted, what is left behind generally is a wet material in suspension form, which may or may not contain reagents harmful to the environment. The amount of waste generated in any of the mining processes is large, in fact, the mining industry is the largest generator of solid waste in Australia. In order to minimise the waste generated within the industry it has become of interest to handle the particulate fluid wastes, or suspensions, at high concentrations, thus removing water and some of the reagents which may be harmful to the environment. The resultant highly concentrated suspension is a non-Newtonian hold Rheology deals with the flow of non-Newtonian fluids; therefore i combination of rheological understanding of high density suspensions. ill conjunction with an understanding of the environmental problems hero' faced by the mining industry, can and has led to improved methods of waste disposal in the industry, ie waste minimisation. This paper describes the progress that has been made in the development of dry disposal technology in the mining and minerals industry in Australia.

Jan 1, 1998

By L D. Munro, S A. Jackson

This paper provides a logical approach to developing a TSF design concept through: • Identifying key properties of tailings and containment structures; • Reviewing underlying principles for effective operation; • Showing how these apply to select an appropriate TMS; and • Demonstrating how to align the TMS to site-specific constraints and TSF design. This approach follows a path of rigorous data analysis independent of discharge parameters (whether low-density slurry, paste or cake disposal) to select the most cost-effective and sustainable approach for any given material or site.

Jul 1, 2021

By J. W. Devon

The coal mining industry is divided into two distinct economic segments based on Coal Supply Agreements. Coal supply agreements generally fall into two categories, spot or long-term, with the selected contract term being driven by the buyer's market expectations, security of supply considerations, fuel tonnage and quality requirements, and economics. Short-term or spot coal purchases are generally market driven and are highly competitive in today's marketplace. Long-term contracts, particularly those involving captive mines and mine-mouth power plants, are commonly driven by considerations other than economics. These other considerations, such as Reserve Conservation and Resource Recovery, Security of Supply, and Maintenance of Levelized Costs may increase the cost of coal, often needlessly and without benefit to the buyer or seller. The basic economic principles which guide the market driven metals industry and generally guide the spot coal sector of the coal industry should apply equally well to the long-term coal supply contract. The artificial constraints imposed as a result of regulated rates of return should be re-examined and in most cases, abandoned. There are many methods of surface and underground coal mining being used today such as, open-pit, contour, mountaintop, and area mining for surface mineable reserves; conventional, standard continuous and super-section continuous miners, and longwalls for deep reserves; and highwall miners, thin seam miners and augers in between. This discussion is primarily directed to surface mining, however the same principles of least cost mining on a Net Present Value basis must be considered in all cases.

Jan 1, 1994

By S. M. Carpenter

In an ever increasing ?carbon? society; management and growth will be measured by one?s carbon footprint (or output). Industries, especially mining, are under an ever increasing scrutiny of carbon, water and environmental mandates. These mandates are measured by the emissions caused by the combustion of fossil fuels. The fundamental building-block for any business, strategic or management decision must be based on an understanding of one?s ?footprint?. The scrutiny is most stringent for the commodities producers, power producers & fuel suppliers in the energy market. An overview of currently acceptable standards, application of those standards and nuances experienced in collecting the data necessary to analyze and complete a company?s carbon footprint will be presented. A lack of regulation, the fear and expectation of new and ever constraining rules, regulation and a change in the federal administration is a recipe for uncertainty in the marketplace.

Jan 1, 2010

By Effie T. Kurt, Jack Wright, J. W. Watkins, Cynthia Pearson

"The analysis of water produced with crude petroleum has interested oil producers since inception of the industry. Records of the first analysis of mineralized water produced from an oil-productive formation are obscure, and references to the first use of brine analyses to assist in solving problems of petroleum production are not available in the technical literature. However, many early reports of the Federal Bureau of Mines 5-8/ and. Federal Geological Survey, 9-11/ as well as articles in engineering and geological placed special emphasis on journals ,12-l4/ the importance, interpretation, and application of water analyses.One of the earliest applications of water analyses, and still a major one today, is for identification of intrusive waters in oil wells. This may be done by comparing the chemical constituents of a sample of water indigenous to the oil-productive formation with those of samples from upper, water-bearing formations within the same general area. Some earlier investigators recognized the need for analyzing samples of all waters encountered in drilling operations. Ambrose15/ stated, in part, ""In wells being drilled, the engineer should grasp every opportunity to get a true sample of water from each sand. . .,"" and, ""The waters of each oil field are chemically different from those of another field."" The validity of the latter observation and the importance of the former one have been borne out by comparing the results of analyses of many samples and noting the differences in relative concentrations of like constituents of waters from the same geological formation in different localities or oil pools."

Apr 1, 1957

By N. O. Lotter

The reliability of a set of flotation results is key to minimizing project risk, either at the commissioning of a concentrator or at the point of implementing an improvement to an existing concentrator operation. High-confidence flotation testing (HCFT) was developed for this purpose and is part of the list of technologies at various scales used by Xstrata Process Support (XPS) in addressing these projects. The methodology is based on two principles: one, to ensure that the ore sample is representative and has been well-blended and subsampled; two, to perform the flotation tests in sufficient numbers of replicates with appropriate quality controls, so as to improve the reproducibility of the test data. Across ten years of research on this methodology at Xstrata Process Support, Sudbury, several improvements to the HCFT method and complementary connections between sampling and quantitative mineralogy have been developed. Two case studies are reviewed. These show the capability of this system in both optimizing an existing concentrator operation and in serving a new mine scenario. Further work to improve the efficiency of this procedure has been identified. Key words: Flotation testing, Flotation

Jan 1, 2010