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By M. E. Gershon

I would like to congratulate Professor Gershon on an idea that is obviously valuable and is certainly new to me. It has, however, to be further developed, in that one can get fallacious results by limiting oneself to positional weights. In the example problem, the positional weight of one block was 8.6 (the 8.0 value in the paper was incorrect) for 36 units in the cone, for a mean block value of 0.239. The positional weight of the second block was 4.4 for 15 units, for a mean block value of 0.293. Surely one would expect the second block to be rated higher. Additionally, the time value of money adjustment cannot be determined by depth, because the time that a block is mined is determined by the mining sequence, not depth. Figure 1 shows a slightly altered version of Professor Gershon’s pit. The overall value of the pit is the same, as are the total values under each of his blocks. The values in the right-hand cone have been reversed top to bottom, and the values in the rest of the pit adjusted to keep the central cone total unchanged. All values have been multiplied by 10. Figure 2 shows the sequence of mining, at three blocks per year, for Professor Gershon’s pit, and Fig. 3, the sequence for a pit under the other block. Table 1 shows the value and discounted value (157. ) of Professor Gershon’s pit, and Table 2 shows similar values for the second pit. It is apparent that the second pit schedule is more valuable than the first.

Jan 12, 1987

By A. Basçetin

Equipment selection in mining engineering is one of the most important decisions that affects the mine design, production planning and economic parameters in open pit and underground mining. Mine planning engineers generally use their intuition and experiences in decision making. Mostly, linguistic variables (the weather is raining, soil is wet, etc.) come into question and decision-makers may not know how these variables are computed. Since the advent of the fuzzy set theory, these uncertainties are easily interpreted in the decision-making process. The development of computer technology and programming of colloquial language with expert systems have considerably reduced decision-makers? burden. This paper reviews the development of a computer programme software called EQS (EQuipment Selection) that automates equipment selection in mining engineering using fuzzy set theory. The EQS with an introduction of the concepts and theories of multiple attribute decision-making, the fuzzy set theory, and EQS applications to mining industry problems with case studies are presented

Jan 1, 2006

By Guillermo Turner-Saad

"Best practice in the economic evaluation of mining projects and operations is based on the integration of geological, mining, metallurgical, environmental, marketing, economic and corporate information and strategies. Fundamentally, the economic evaluation takes into account mining, blending, stockpiling, processing, smelting, refining and marketing ore resources with grades estimated by geostatistical methodologies.Nevertheless, a realistic economic evaluation consists of a concurrent and integrated optimization process that maximizes the concentrates or products of liberated and selected ore minerals from mineral deposits. The optimum solution is obtained through a trade-off among mining, blending, stockpiling and processing ore reserves with distinct mineralogy and texture characteristics. The concurrent optimization determines both the practical mining sequence of ore reserves and the dynamic and robust mineral processing flowsheet design over the expected life of mining projects and operations.A combined risk-adverse and concurrent optimization process takes into account the spatial uncertainty of the mineralogy and texture characteristics of ore reserves. Additionally, a variety of mineral processing linear, non-linear, additive and non-additive parameters modeled spatially. The spatial uncertainty of these ore reserves characteristics and parameters has a direct impact in the expected mining sequence, mineral processing flowsheet design, concentrates or products quantity and quality, and economic value of mining projects and operations.Geometallurgical domain constrained stochastic geostatistical methodologies and multivariate mathematical models are applied for spatial uncertainty modeling of ore reserves characteristics and parameters. These mathematical models correlate the mineral processing liberation and selectivity responses of the mineralogy and textures within each geometallurgical domain. These models, in turn, are defined based on results of mineral processing and environmental testwork of unbiased and representative samples chosen for their variability. These samples are selected within mutually exclusive spatial geometallurgical uncertainty domains with similar mineralogical and textural characteristics in mineral deposits.Geometallurgical domains are defined by applying and combining multivariate statistical analysis and implicit modeling methodologies. These involve determining and constraining mineral processing liberation and selectivity properties explicitly contained in the extensive and integrated exploration drillhole database."

Jan 1, 2010

The current methodology to design stope support systems in South African gold and platinum mines is based upon the tributary area concept. The discontinuous nature of the hangingwall rock is not adequately addressed, and mechanisms leading to rock mass failures between adjacent support units are poorly understood. The work reported here aims to formulate a basis for quantifying support mechanisms and gain insights into the influence of rock discontinuities on stable hangingwall spans. Numerical models are used to qualitatively investigate the stress transfer from the support units to the discontinuous hangingwall. Stable hangingwall spans are quantified by considering two failure mechanisms, namely (i) beam buckling, and (ii) shear failure due to slip at the abutments. The output of the proposed design methodology is appropriate site specific support spacing, based on discontinuity spacing and orientation. The method is particularly suited to mines at intermediate and great depth, where typically the hangingwall is highly discontinuous due to face parallel mining induced fractures. Results of parametric studies show that with increasing in situ compressive hangingwall stress, beam thickness and friction angle, hangingwall stability is increased, leading to wider stable hangingwall spans between adjacent support units.

Jan 1, 2000

By Lumley G, Rowlands D

The overburden slusher (OS) is proposed as a stripping tool that is expected to find application in overburden stripping operations including open cut coal and oil shale mines. OS is expected to combat the effects of increasing depth on the productivity of conventional dragline stripping.Although previously developed stripping techniques have included the use of drag scrapers the OS is sufficiently different as to constitute a new stripping method.A study undertaken at the University of Queensland during 1985 is believed to be the first major study on the use of the OS and preliminary economic results are very encouraging. It appears that the OS has the capacity to remove overburden at a cheaper unit cost than the equivalent powered dragline stripping machine at any comparable depth of overburden. The OS is not adversely affected by increasing stripping depth to the same extent as a dragline. In addition, the action of the OS machine allows for the lowering of spoil face angles, thereby reducing spoil slope stability problems encountered in deep open cut strip mines.

Jan 1, 1986

By C. J. Farrow, M. J. Smith

"Bechtel has managed a number of test programs to establish autogenous grinding circuits and size mills for a variety of ores.This paper outlines the procedures whereby bench scale and pilot plant tests are used to select the most efficient circuit to grind the range of ore types likely in the mill feed.Five examples are given. One example traces the development of a pilot plant program; it shows how bench scale Work Indices provide a target for the grinding power requirement of an ore and relates how pilot circuits are changed as a result of interpreting the results from preceding tests. The other four examples relate the interpretation of the test results to provide design data; they illustrate a number of phenomena which have been observed.INTRODUCTIONConventional crushing and grinding circuits can be specified from bench scale test data such as Bond Work Indices. Bond Indices have been correlated to a large number of rod and ball mills and by applying appropriate factors, mills can be sized from the Work Index.For autogenous or semi-autogenous grinding circuits, bench scale tests are not sufficient to be able to specify the circuit and size of the mills for a commercial plant. It is necessary to run a series of pilot plant tests to determine how the ore behaves."

Jan 1, 1982

By John Brulia

You’ve probably heard the old expression, “The more things change, the more they stay the same.” But the adage doesn’t seem to hold much water when it comes to making a telephone call on the road. Thirty years ago, a “powder hound” had to stop his 2-wheel drive vehicle at either a roadside diner or a telephone booth to make a call using a public telephone. But, fast-forward to 2007, and a contemporary “explosives engineer” driving his or her 4-wheel drive vehicle simply makes a call “on-the-fly.” The fundamental difference between these two eras is the result of the introduction and the proliferation of cellular or wireless technology. On the one hand, this fundamental difference is much welcomed in the form of personal and business conveniences; and improved productivity. On the other hand, this fundamental difference creates a new set of un-welcomed conditions causing a potential “digital danger.”

Jan 1, 2008

By Jon R. Maki

"EVTAC, an iron ore mine in Minnesota, had trouble meeting the customer’s pellet silica requirements. In addition, the mine plan was moving towards a lower grade ore and funding was not available for plant improvements to compensate for the change in ore or improving quality. Small changes to optimize various processing equipment resulted in significant improvements in both quality and productivity; for example, productivity on one mill line increased by 10% while producing lower silica concentrate. This paper will provide the methodology that allowed EVTAC to improve quality and productivity through process optimization with little capital investment.INTRODUCTION EVTAC, an iron ore mine in Minnesota, had trouble meeting the customer pellet silica requirements. In addition, the short-term mine plan was changing to a lower ore grade. Because of limited funds, EVTAC did not have the capital for investing in the plant to compensate for the ore change or to make improvements to lower product silica levels. Small changes to optimize process equipment resulted in significant improvements in quality and productivity; for example, one mill line feed rates increased by 10% while also producing a higher quality concentrate. These changes were sufficient enough to allow the mine to lower the target ore grade beyond their initial goal. At one time, a $3M flotation facility was considered as a way to meet quality with the new ore grade. However, the process changes were able to accomplish the same silica reduction with roughly a $50,000 investment in VFDs for sump controls. This paper will discuss some of the modifications that allowed EVTAC to meet the quality and production objectives with little capital investment. It also discusses the methodology used to make these process improvements."

Jan 1, 2014

By L. Maday, V. J. Perrone, M. B. Gilbert

INTRODUCTION The Brightwater conveyance system project in King County, Washington consists of constructing about 21 km (13 mile) of effluent and combined influent and effluent tunnels. The influent tunnels will collect sanitary sewerage from the service area and convey it to the new wastewater treatment plant (WTP) site at Route 9 in Woodinville, Snohomish County, Washington. The effluent tunnels will convey treated effluent from the WTP to an outfall at Puget Sound. The tunnels will be constructed primarily under residential areas, busy suburban roads and state highways. This 21 Km (13-mile) soft ground tunneling project faced many design challenges because of the geologic and hydrostatic conditions, long tunnel reaches, and large overburden depths. Boring depths typically varied from 45.7 M (150 ft) to 114 M(375 ft) with a maximum depth of 185.6 M (566 ft) deep. Conventional empirical methods for non-mountain terrain based on a 1:1 ratio of drilled footage per foot of tunnel bore (National Research Council, 1984) for evenly spaced borings provided a good start for the Phase 1 explorations. However a continuation of this approach with closer spacing was deemed inadequate by the geotechnical team for efficiently allocating geotechnical exploration resources for the final design. This paper presents a rational approach that was used to evaluate the value of a particular geotechnical exploration boring, pump test or other in-situ test. The method of analysis, which was initially developed for rock tunnels (Einstein et al., 1978), was modified for the Brightwater project. The method considers the potential construction cost risks resulting from variable geologic conditions, the cost and reliability of the geotechnical exploration and the earned value (cost risk reduction) of performing the geotechnical exploration. PROJECT DESCRIPTION In total the land portion of the conveyance system will include approximately21 Km (13 miles) of tunnels ranging in size from 3.0 to 5.2 M (10 to 17 ft) minimum inside diameter with overburden depths of 30.0 to 168 M (100 to 550 ft) and

Jan 1, 2005

By James L. Fenton

In its unending search for the raw materials that the affluent society of today requires the mining industry has found it necessary to go to great depths, in many cases, to produce these materials. Inherent with this problem is the insufficient technology relating to improving extreme environments that the mine personnel are exposed to. In this dissertation, the sources of heat flow into a mine along with the various effects that this heat has on the mine personnel are investigated. The object of dissertation is to compile all the available published information pertaining to these underground heat and their effects into one paper. This will provide the mining industry with an available easy-to-use to aid in the determination of mine ventilation requirements as the mines are in the phases of original planning or being extended to depth. Areas of significant, deficiencies it knowledge have been disclosed during this overall appraisal. Recommendations on important basic research needs are out lined for future consideration by Federal or industries sponsorship. This thesis should serve as a stimulus lo, future well-organized research efforts in the area of underground heat sources and their control.

Jan 1, 1973

By Zeljka Pokrajcic

Crushing and grinding, or comminution, circuits are the most energy intensive process of a mineral processing plant. Comminution involves the physical size reduction of an orebody to a particle size sufficient for recovery of the mineral values. However, the comminution process remains inherently inefficient. The inefficiency is a result of the operating nature of comminution devices such as grinding mills, where transfer of energy between grinding media and particles in unconstrained and completely random. New comminution circuit design strategies are presented in this paper. The aim of the new strategies is to improve the overall efficiency of the comminution process and reduce the total energy consumption of a comminution circuit. The energy efficient strategies include the: ? rejection of coarse size liberated gangue from the comminution circuit and further downstream size reduction ? use of more efficient grinding and crushing equipment ? the selection of coarser particle product sizes to alleviate the increased energy intensity required to achieve finer product sizes Singularly and when combined, these energy efficient strategies can significantly decrease the overall energy consumption of a comminution circuit. This paper also explores the financial impact of certain energy efficient strategies using an analysis tool called EcoNomics?. It shows that substantial financial gains can be made by including more efficient technologies and methods in comminution circuit design.

Jan 1, 2010

THE irregularity of the Mount Morgan ore body presents problems other than those for mining only. For irregularity of outline is coupled with irregularity of grade, and the ore varies so rapidly from profitable to non-profitable, and from highly siliceous to highly pyritic, that the task of estimating quantities and values of ore reserves is manifestly rendered a difficult one, while the actual disposal Of the broken ore demands constant supervision.Four classes of ore are handled. The oxidized ore, cheaply mined and cheaply treated, is obtained by quarrying from the top of the mountain. Below the 315-ft. mine level (measured from the original summit) sulphide ore comes in, and this is divided into siliceous sulphide ore (too siliceous for economic smelting), sulphide ore suitable for smelting, and ore too poor either to be smelted or to be treated by wet process with the siliceous ore. It is with these three latter descriptions of ore that this paper principally deals.Although the output from most stopes in the mine may usually be presumed beforehand to be either smelting or wet-treatment ore...

Jan 1, 1910

New Zealand depends on foreign investment for economic development. This also applies to the development of New Zealand's mineral resources. For this foreign investment to happen there must be some incentives to attract the investment. While prospectivity is the dominant parameter considered by investors it is not a variable that can be changed, only the perception of New Zealand's prospectivity. Other parameters likely to be considered are sovereign risk, red tape, green tape, land access, civil unrest, land claims, social risk, labour relations, infrastructure and natural disasters. Regulators and political will can vary some of these parameters. Where New Zealand fits internationally can be measured by investors' perceptions of these parameters. Following on from these perceptions New Zealand can be seen to have advantages in some areas and be disadvantaged in others. How to deal with the disadvantages to give investors confidence is not easy in the New Zealand environment where the development of mineral resources plays a small part in an economy dominated by agriculture. Added to this is the current global state of the minerals industry which offers even more of a challenge to attract foreign investment to develop New Zealand's mineral resources.

Jan 1, 2000

The works of Metal Manufactures Ltd are situated at Port Kemblam NSW, within a few hundred yards of a deep-water harbour. At present they occupy about 26 acres, and ample provision has been made for future extensions. Rail connection exists between various parts of the Works and the main South Coast Railway, the harbour jetties and the adjacent copper refinery of The Electrolytic Refining and Smelting Co Ltd. A plan of the works is shown in Fig 1.The company was incorporated in March 1916, and commenced production of copper wire in June 1918. Early in 1920, tube manufacture was undertaken, followed by telephone cable mnufacture in 1923. Today the Works consist of five principal sections: Founrdy, Tube Factory, Wire Factory, Cable Factory and Case and Drum Factory. Whilst the last four are engaged in producing the finished materials for despatch from the Works, the first-mentioned is engaged in producing copper, brass, and other non-ferrous billets for use in the Tube and Wire factories. In addition, there are Engineering and Metallurgical Departments supporting the manufacturing sections, and in these, as well as in all other sections of the Works, extensions have been carried out from time to time to provide for increased output and new types of products.

Jan 1, 1938

Develop tools that mine personnel can use to comply with 30 CFR,Part 47. Background The new MSHA rule, 30 CFR, Part 47 (also known as the HazCom rule), requires all mines to develop a written program to track hazardous chemicals at their sites. More specifically, the rule requires that mines list all chemicals and determine which are hazardous; develop a written Hazard Communication Program; label all containers used to store hazardous chemicals; obtain or develop Material Safety Data Sheets (MSDS) for all chemicals stored or produced; provide miners with training in working around hazardous chemicals; and make information about hazardous chemicals available to all workers. All mines with six or more employees must have complied with the new rule by September 23, 2002, and mines with five or fewer employees will have to be in compliance by March 21, 2003.

Mar 1, 2003

By Eugene McAuliffe

THE heavy shrinkage in the production of bituminous coal has reflected adversely in the matter of tonnage produced by stripping arid mechanical loading machinery. The purchase of stripping and underground loading equipment has likewise been circumscribed. How- .ever a growing percentage of bituminous coal is being loaded by stripping and mechanical loading machinery. This situation is due to the fact that numerous strip pits were able to operate in Illinois and Indiana when under- cover mines were subjected to labor interference, a further advantage gained by their ability to produce and market coal at a price below that of the undercover mines. The mines equipped with mechanical loading. apparatus have enjoyed more continued operation for the double reason that the companies using coal-loading machinery are, generally speaking, more substantial and in better financial condition than many of the smaller properties who maintain hand-loading methods, and the market advantage due to lower production costs also reflects to the advantage of the undercover mines using mechanical loading equipment. Where a number of mines are con- trolled by one company, those not equipped with loading machinery and suffering from higher producing costs have often been closed, with the available tonnage concentrated in the more modernly equipped mines.

Jan 1, 1933

By Steve Kral

In 2002, many in the mining industry — companies, academia and government — realized that the industry would soon be facing a serious shortfall in salaried and hourly employees. Depending on whose numbers are to be believed, 20 percent to 50 percent of current mining professionals are expected to retire within five to 10 years. And there are not enough students currently enrolled in mineral-related programs to the fill the need. Part of the impending shortage in professionals was brought on by the industry’s negative image, which discouraged students from enrolling in mining engineering programs. Another part was that the industry was in the doldrums and was seen by the public as a dying industry.

Jan 1, 2006

By E. Demir

Transportation cost is the dominant cost and accounts for almost half of the total mining cost in surface mining. Therefore, determining transportation cost is critically important for the economic feasibility of mining projects. Turkey produces around 85 million tons of lignite per annum. The biggest state-owned company, Turkish Coal Enterprises (TKI), accounts for 43 per cent of the country?s total lignite production. Around 85 per cent of the produced lignite is used in power plants for electricity generation and 15 per cent is used for domestic heating in cities and urban areas. On behalf of the Turkish government, TKI distributes around 2 Mt of lignite annually, at no cost to poor needy families countrywide in accordance with Social Assistance and Solidarity Funding aid. Subcontractors are utilized for lignite transportation, and conflicts arise due to the different transportation cost calculations at different mines. A robust model that provides unbiased cost estimations is therefore of paramount importance. This paper presents the transportation cost estimation software, NAKMAL, that has been developed for estimating the transportation cost of lignite from the mine face, including excavation and loading, to various final destination points through five different transportation scenarios. NAKMAL was designed using VisualStudio.NET, validated using field data and some case studies, and it is currently being used by TKI for calculation of transportation cost country-wide.

Jan 1, 2012

The method of investigation was to study the distribution of ore in great detail, to make a thorough structural study of the lode and the mine area, and then to compare the results of the two studies. Such a comparison usually reveals a very close relationship between geological structure and ore distribution, and can often lead to important conclusions which would not be reached in the ordinary working of a mine.The Triton mine lies 30 miles E.N.E. of Cue, or 380 miles N.W. of Kalgoorlie, in typical pre-Cambrian rocks, consisting of gTeenstone lavas and tuft's, interbedded with slates and some sediments, and intruded by granite and porphyry. Fig. 1 (at end of paper) is a longitudinal section of the mine and shows that the workings consist of the main North Emu and the smaller South Emu, separated by a distance of about 1 of a mile. Both orebodies occur on the same lode, which strikes north and south and dips practically vertically. On the same line, and of 1/2 a mile and a mile respectively to the north of the North Emu, are the small Rand and North Rand workings, where a big width of lode material has proved to be very low grade. In the North Emu the lode width averages 12 to 15 feet; it is seldom less than 5 feet and in places reaches 30 feet. In the South Emu the lode is wide, but only portion of it is payable.The lode is a mineralised bed occurring between massive lava flows on the east and a mixed series of tuft's and thin lava flows on the west. The lode material is hard, fine grained, and dark coloured, and generally has a faint banding which is believed to indicate a tuft'aceous origin of the original lode rock. Microscopic examination shows that the original lode rock has undergone considerable albitisation;' there has also been considerable formation of biotite which gives the lode material a characteristic sheen. The mineralisation consists of abundant fine pyrite, which is auriferous, and a lesser development of pyrrhotite which is, however, barren of gold.THE OREBODIES AND THEIR CHARACTERISTICSThe distribution of ore is best studied from gold contours, as these reveal features that cannot be detected in an ordinary assay section. Gold contours (see Fig. 3) are developed' by plotting the width and grade of all development and stoping assays throughout the mine on a longitudinal projection, representing each sample by a coloured dot according to a suitably chosen range of assay values, and then outlining areas of similarly coloured dots (see H. J. C. Conolly, Econ. Geol., April, 1936). Both width and grade must be taken into account and the simplest method of gold contouring is to use dwt.lft. values, but difficulties arise here with big widths of low grade and small widths of high grade ore. To choose an extreme case, 30 ft. of 2 dwts. and 2 ft. of 30 dwts. both equal 60 dwts.lft., and would therefore be given the same value in dwt.lft. contouring...

Jan 1, 1943

By E. Pizarro, A. Videla, G. Compan

One of the main problems related to mining investment decisions is the use of accurate prediction models. Metallurgical recovery is a major source of variability, and in this regard, the Chuquicamata processing plant recovery was modelled as a function of geomining-metallurgical data and ore characteristics obtained from a historical database. In particular, the dataset gathered contains information related to feed grades, ore hardness, particle size, mineralogy, pH, and flotation reagents. A systemic approach was applied to fit a multivariate regression model representing the copper recovery in the plant. The systemic approach consists of an initial projection of the characteristic grinding product size (P80), based upon energy consumption at the particle size reduction step, followed by a flotation recovery model. The model allows for an improvement in the investment decision process by predicting performance and risk. The final geometallurgical model uses eight operational variables and is a significant improvement over conventional prediction models. A validation was performed using a recent data-set, and this showed a high correlation coefficient with a low mean absolute error, which reveals that the geometallurgical model is able to predict, with acceptable accuracy, the actual copper recovery in the plant.

Jan 1, 2015