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By F. Dehghani, B. Rezaie, T. Ghosh, A. Sachan

Comminution is an integral part of the mineral extraction process. However, the influence of the comminution method (ball and rod mills) on silica and magnetite particle shapes has not been substantially investigated. Shape parameters for fractions of -250+212, -150+125, and -106+75 μm sizes were examined utilizing a scanning electron microscope and a Clemex vision PE image analysis system. The silica particles displayed higher elongation and flatness parameter values for rod mill products, but roundness and relative width parameter values of rod mill products are less than that of the ball mill products. Magnetite particle elongation and flatness parameter values of ball mill products in fraction sizes of -250+212 and -106+75 μm are larger than rod mill products, but roundness and relative width parameter values of ball mill products are smaller than rod-mill products, but for the -150+125 μm size range the result is converse. Furthermore, particle elongation and flatness increased with decreasing particle sizes of silica, whereas, roundness and relative width decreased for both Ball and Rod Mills. In case of magnetite, ball mill products displayed an increase of flatness and particle elongations with decreasing particle sizes but flatness increased and roundness and relative width decreased. Similarly for rod mills, magnetite fractions of -150+125 μm were found to have the largest values of elongation and flatness. INTRODUCTION Comminution alters the size and shape, causes lattice distortion, changes chemical composition, surface area, surface-free energy, and polymorphic transformation of all materials. The quantity and quality of such changes depend on specifications of the material feedstock, the type of mill being utilized, the specific energy input, ambient temperature, and environmental pressure [1]. The shape difference between the milled products depends on different grinding mechanisms and the respective breakage principles that these mechanisms depend on [2, 3]. With decreasing particle sizes, the nature of the particle surface become crucial [1]. The influence of the breakage technique has been found to be non-trivial and heavily dependent on the type of grinding mill used for particle size reduction [4]. Shape is an important industrial parameter for predicting particle behavior in downstream processes. The shape parameter affects the way particles burn, compact, are recovered, flow in fluids, sinter, float, agglomerate, fluidize, interact with pulmonary tissue, cut, abrade, react with chemicals, form structural materials, and retain and permit fluids to flow [5, 6]. The distribution of particle sizes and shapes are important for mining, civil and chemical, pharmaceutical, and various other industries with interest in the population modeling of atmospheric dusts, smoke, and grit [1, 3, 6]. The shape parameter not only affects the chemical, physical, surface properties of particles but is also important for downstream processes [5, 6]. Image analysis has been found to provide detailed information about size and shape of the particles and can be used for the control of product quality [4].

Jan 1, 2019

By J. Drelich

The wetting behavior of liquid polymers at solid surfaces and the adhesion forces involved at polymer-filler interfaces should always be considered in the fabrication of high quality polymer composites, including those made with mineral fillers. Spontaneous polymer spreading over the filler surface is a basic condition in the fabrication of the polymer-mineral composites. In this regard, the wetting and adhesion characteristics of polymer-mineral systems are reviewed in this contribution. It appears that several aspects of wetting phenomena at mineral filler surfaces are not well described in the literature and require further systematic study. Specifically, it is clear from this review that efforts should be made to determine the effects of mineral surface contamination (including surface hydration) on wetting and adhesion phenomena, and to determine the wetting characteristics of molten polymers at mineral filler surfaces. It is expected that any improved fundamental understanding of wetting and adhesion phenomena for the polymer-mineral composites will provide the basis for further technological development.

Jan 1, 1995

By Joshua Cole, Joshua Sovechles, Christian Cardoso, Guillermo Bermudez, Martta Hirsi, Joshua Dettamanti, Rabia Abbasi

The implementation of technological advancements in flotation is key to optimize performance in mining operations. Consequently, flotation cell’s performance is highly dependent on the effectiveness of the mixing mechanism. A more efficient flotation mixing mechanism is likely to improve metallurgical performance and optimize energy consumption, which is the motivation for Metso’s journey to develop the latest iteration of FloatForce®. Looking to test the new design at plant scale, Metso approached the Kennecott Copperton concentrator, which is continuously looking for different venues to improve metallurgical performance. In this context, a test campaign was conducted to implement this new flotation mixing mechanism in their rougher circuit during 2024. The industrial trial consisted of several sampling campaigns assessing different operational parameters for comparison purposes around a 300m3 flotation cell. The effect of the new flotation mixing mechanism on the cell’s power draw was also studied. The results of this trial at Kennecott are presented in this paper. Overall new flotation mixing mechanism, FloatForce+ was seen to perform as well as the original FloatForce.

Feb 1, 2025

By K. Terhaar, K. Prisbrey

The objective was to determine operating protocols for a lead and silver column flotation cleaner, being considered for installation at Sunshine Mining & Refining Co.’s Kellogg mill in Northern Idaho. In this column, tetrahedrite and galena were floated, and pyrite and other gangue minerals, including siderite and silica, were depressed. The procedure was to develop a dynamic simulation using a linear transfer function approach. The transfer function related cause and effect variables such as the influence of collector and depressant dosages on recovery and grades. Bench-scale flotation tests followed by pilot column testing provided the data used to develop a linear transfer function. The transfer function was derived using a spreadsheet. This model was applied to simulate how the flotation column could be made to respond to disturbances in feedgrade. The results were that xanthate, zinc sulfate, and sodium cyanide were found to be suitable controls for grade and recovery. Simulations showed the best sequence of manipulations of these reagents, and these sequences were useful for future operator training. The conclusion was that linear transfer functions were able to simulate lead and silver recovery, develop scenarios for operator training, and provide a foundation for future on-line control.

Jan 1, 1999

By Rambabu Pothina, Rajive Ganguli

The economics of a mineral processing circuit is dependent on the numerous sensors that are critical to optimization and control systems. The sheer volume of sensors results in mines not being able to keep the sensors calibrated. When a sensor goes off calibration, it results in errors which can severely impact plant economics. Normally, these errors are not detected until the error grows and becomes a large (“gross”) error. Undetected errors are not remedied until the next calibration, which on average are a year apart Beamex (2019) [1] across all industries. Classical statistical methods that depend on linear relationships between input and response variables are typically used to find gross errors, but are not effective for highly non-linear and non-stationary operations in mining and mineral processing industries. Calibration of sensors is time-consuming and generally requires physical intervention that results in equipment downtimes causing production losses. Therefore, in situ detection methods are warranted that do not require physical removal of sensors to compare with standard measurements or well-calibrated sensors. Data-mining based techniques and algorithms have high success rate in tackling such problems. This paper presents results from a groundbreaking multi-year big data research project whose goal was to develop data-mining-based original techniques in a multi-sensor environment to identify when sensors start to stray, rather than wait for errors to grow. The carbon stripping (gold) circuit in the Pogo Mine of Alaska was selected for this project. Maintaining strip vessel temperatures at optimum levels is crucial for maximizing gold recoveries at Pogo, and hence the focus was on the temperature sensors of the two strip vessels. An automated algorithm to detect errors in strip vessel temperature sensors was developed that exploited data from multiple sensors in the strip circuit. This algorithm was able to detect with a high success rate when bias errors of magnitude as low as ± 2% were artificially induced into strip vessel temperature data streams. The detection times of about 1 month were much less than the industry average calibration frequency of 1 year. Thus, the algorithm helps detect errors early, without stopping the circuit. The algorithm alarms can serve as triggers when calibrations are done. Experimental methodology along with results, limitations of algorithms, and future research are also presented in this paper.

By R. C. Troxell

Alternative methods of analyzing data acquired by the Morenci copper concentrator process control instrument-computer system are presented. Experimental measures of ore characteristics, for proposed feed forward control, are introduced. These include on-line indexes of ore hardness, ore density, ore dusting, and ore color. Comparison of metallurgical results before and after computerized process control implementation, allowing for differing ore grades, oxidation, hardness, and fineness of grind, also is described.

Jan 1, 1979

By James Paone

Drillability of rocks by mechanical means is closely related to the physical properties of the respective rocks, Various approaches by previous investigators on rock drillability are presented, as well as recent techniques studied by the Bureau of Mines. The studies show drillability concepts based on (1) theoretical drilling equations derived from laboratory drilling experiments extended to field drilling results and on (2) a statistical method where multiple regression analysis is used to develop a prediction equation for drillability.

Jan 1, 1966

By Fred D. Wright, Stefan H. Boshkov

12.1-BASIC AND PARAMETRIC CRITERIA IN THE SELECTION, DESIGN AND DEVELOPMENT OF UNDERGROUND MINING SYSTEMS STEFAN H. BOSHKOV AND FRED D. WRIGHT The criteria governing the selection of an underground mining system relate to several factors the importance of which varies with geographic location, the state of development of the industrial technology, the economic climate in the Nation and, perhaps, in the world-all these as functions of time. Thus, the best choice of a mining method depends upon sets of definable and undefinable values for numerous factors that may be considered fixed at the precise point in time. Subsequent changes in economic and/or technological developments may necessitate modification or complete revision of the existing mining system. A classification of criteria for selecting a mining system must be based on the broadest definitions. Specific cases may present simple solutions or pose very intricate questions, the answers to which are frequently based on judgment rather than explicit logically reasoned and derived results. Specific criteria may be of negligible consequence in some instances and of overriding importance in other cases. It would be foolhardy to attempt to point out, in the limited space available, all possible variations and interplay of factors, as well as to define the setting in which this interplay can take place. The reader is, therefore, referred to the case histories described in the subsequent parts of this section where actual practice will point out the variability of the problems encountered in the selection of a mining method. A popular thesis suggests that the proper approach to selecting the method of mining should be rooted in the inverse solution, whereby the limitations of the various methods in use serve as criteria to eliminate most of these methods from consideration in the specific case. This narrows the ultimate selection to one or perhaps two most appropriate methods. At this stage, a critical comparison analysis will lead to the ultimate choice. Although such a negative approach un¬questionably is valid in discarding obviously inapplicable mining systems from consideration, it falls short in defining the best system, which in practice quite often turns out to be a variation of a textbook standard, or a combination of two or more such standards. Because the deployment of capital and manpower over a long-term commitment closely follows the selection of the mining system, the decision-maker can well afford to spend a great deal of time and effort in evolving the optimum solution for the peculiarities of his specific case. Within the basic engineering tenets of economy and safety to which the design of a mining system must adhere lie numerous factors of constraint which may be grouped, somewhat arbitrarily but for ease of discussion, into several categories. The criteria that enter into the choice of a mining method derive from the following groups of factors: 1. The shape, size and spatial position of the ore deposit.

Jan 1, 1973

By Juan J. Monsalve, Mario Karfakis, AMAN SONI, Nino Ripepi, Jim Hazzard

Pillar collapses are events that due to their severe consequences can be classified as high risk. The design of pillars in underground room-and-pillar operations should migrate to risk-based design approaches. The authors of this work proposed a risk-based pillar design methodology that integrates stochastic discrete element modeling for pillar strength estimation, and stochastic finite volume modeling (FVM) for stress estimation. This paper focuses on the stochastic FVM component for stress estimation. The mining and geomechanical aspects of a case study mine (CSM) are described and pillar stresses are estimated by using three approaches: (1) analytical solutions, (2) 2D finite element modeling, and (3) 3D finite volume modeling. This operation extracts a 30° dipping deposit, which makes current underground stone mine design guidelines inapplicable for this CSM. This work compares results from each stress estimation approach and discusses uses the point estimate method as a simplified stochastic approach to evaluate the effect of rock mass elastic properties variability on pillar stress distribution. Results from this work show that the three estimation approaches lead to different estimations, possibly, due to the wide range of assumptions each estimation approach considers. It was also determined that the horizontal to vertical stress ratio has a significant impact on pillar stress magnitude. Therefore, it is recommended to perform in situ stress measurements, or assume worst-case-scenario values to account and reduce uncertainty due to this parameter. The stochastic stress estimation approach used in this paper provides results that can integrate a risk-based pillar design framework.

Sep 24, 2022

By R. L. Loofbourow

R. L. LOOFBOUROW 26.1-WATER FLOW, USE, EFFECTS, CONTROL Sec. 4 discusses ground water as a mineral resource. This section deals wits its control. 26.1.1-IMPORTANCE Flows of water have an important effect on the cost and progress of many deep excavations. The existence of water limits the methods which can be used in some and presents hazards in others. Lowering the water table may reduce the flow of springs and wells, with legal liability. Some mine water is used directly, some must he treated before discharge, and some contains dissolved solids which can be recovered profitably. Loss of life, property and production from flooding is grim, yet scores of mines have worked safely for generations under ground-water reservoirs, lakes and even the sea. The need for better control of mine water is measured by the severity of recent floodings, concern with the quality of the effluent, and direct and indirect costs of working wet ground. There are improvements in freezing in shaft sinking. pumps and their controls, treatment of mine water before it is pumped, bulkhead construction and certain efforts to reduce inflow. 26.1.2-PUMPING COST VS. COST OF WET WORK Direct operating and capital costs of pumping are more evident than indirect items, such as provision of extra standby power and maintenance facilities, The total of all these items is the cost of pumping water from an excavation. This is only a part of the extra cost of working wet as compared to dry ground. Less productive methods, less efficient equipment and more expensive explosives may have to he used in wet work. Wet rock plugs certain equipment. Maintenance is higher and labor less efficient. The cost of any means of keeping work drier should he weighed against the higher cost of working wet. The true difference in the cost of working wet ground, compared with dry, probably is known at only a few places (see checklist of cost items. Sec. 26.4.13). An extreme comparison of mining wet and dry ore is available from Ambrosia Lake, N.M. (Fig. 26-1). Between 1963 and 1967, a wet and a dry mine were worked by the same company under conditions otherwise comparable. Average operating cost at the wet mine, pumping 1,600 to 1,800 gpm. was $16.06 per ton of ore. The comparable figure for the dry mine was $7.50. Principal differences included the fact that the wet mine was worked from drainage levels below the, ore with rail haulage, the dry mine in the ore with off-track equipment loading and hauling to the shaft. In the wet mine, ore packed in chutes, cars and skips and froze in surface bins, stockpiles and trucks. Wet-mine costs included drilling drain holes, building and maintaining ditches and pumping water containing abrasive solids.

Jan 1, 1973

By Muhammad Zia-ur Rehman, Sajjad Ahmad Baig, Gao Lei Fu, Muhammad Mohsin, Sobia Naseem

The environmental sustainability is linked back to human sustainability; the sustainability development comprises the environment, society, and economics. This study mainly focused on mining sustainability and its impact on the environment of Pakistan. For measuring the level and environmental mining sustainability nature to Environmental Impact Assessment (EIA) of the world’s second largest salt mine “Khewra,” Folchi and Phillips environmental sustainability mathematics (PESM) models are applied. The results indicated that Khewra was deemed to be potentially sustainable for the environment and quality of salt. The results suggest the delicate balance of maintaining sustainability successfully, regarding the mining process in Pakistan which has been affecting the local environment and community so badly. The paper lays emphasis on the potential significance of the model’s application for the attainment of sustainable mining goal. This study is essential for researchers,

May 11, 2020

On Dec. 20, 2013, an 8-m (26.2-ft) diameter Robbins hybrid single shield/earth pressure balance tunnel boring machine (EPB TBM) was launched to bore the Grosvenor decline tunnel for Australia?s Anglo American coal mine. The machine was built using onsite first time assembly (OFTA) in order to fit within a tight project schedule. Assembly at the remote jobsite near Moranbah, Australia took about four-and-a-half months, and then the machine was walked down into a launch tunnel. Two decline tunnels, at grades of 1:6 and 1:8, will be used for mine access to new coal seams. The hybrid machine is tackling mixed ground conditions ranging from sand and clay to varying types of sedimentary hard rock up to 120 MPa UCS, as well as coal seams. Methane gas is expected to be present throughout the tunnel, so the machine has been designed as explosion-proof-compliant to ERZ-1. ?Grosvenor is the first underground coal mine in Queensland to use a TBM for drift construction,? said Glenn Tonkin, Grosvenor project director. ?We are proud to be pioneering this technology.? Only about 300 m (984 ft) of ground in each decline tunnel is expected to require EPB mode, while the rest of the tunnel will be bored in hard rock mode. Thus, the design was optimized toward hard rock excavation.

By SANDEEP KUMAR JENA

This review work reports the recovery of potassiumfromdifferent rocks and mineral sources. The global demand for potassiumis rising consistently due to the growth of agricultural production. A major portion of the world potassium production is consumed in making of fertiliser; however, other uses include those in pharmaceutical, glass, ceramic, food and detergent industries. The availability of soluble potash minerals (sylvite, kainite and carnallite) in different countries like Canada, USA, Israel and Russia makes them as major potash producers, whereas agricultural-based countries like Liberia, Somalia, Central African Republic, Thailand, Indonesia and Malaysia including India meet their potassium requirement through import only. On the contrary, the availability of huge potassium-bearing rocks/minerals (like nepheline syenite, feldspar, mica, glauconitic sandstone) in these countries containing around 4–17% K2O would be a prospective for commercial production of potassium. The potassium recovery from minerals/rocks is very complicated due to the uniform distribution of potassium throughout the crystal structure. Different physico-chemical separation methods like bioleaching, chemical leaching, flotation and roast leaching have been discussed for the successful recovery of potash values from these rocks/minerals. However, the recovery of potassium from hugely available seawater using the chemical precipitation, solvent extraction,membrane separation and ionic exchangemethods is not cost-effective due to the low concentration of potassium.

Aug 31, 2020

By R. Y. Wan

Acid ferric sulfate solution has been used for heap and dump leaching of low-grade chalcopyrite ores and is being considered as a possible lixiviant for the hydrometallurgical processing of copper sulfide concentrates. For many years, researchers have attempted to explain the leaching behavior of chalcopyrite, since the reaction rate kinetics are extremely slow and seem to be significantly influenced by the nature of the reaction product. A summary of conclusions drawn from reported literature on chalcopyrite leaching is found in the paper by Munoz, Miller, and Wadsworth(1) and more recently by Dutrizac.(2) Lowe(3) and Jones and Peters (4) attributed rate control to a surface reaction. Linge,(5) Dutrizac,(6) Bauer,(7) and researchers at the University of Utah(1,8) reported that the reaction rate is limited by transport in the chalcopyrite lattice or through the elemental sulfur reaction product layer. Munoz et al.(1) presented a model, derived from the Wagner theory of oxidation, which is based on the formation of a protective sulfur layer with rate control by electron transport through the insulating sulfur layer. By utilizing Wagner's parabolic oxidation relationships, (9) the following equation was obtained: [ ] where a is the fraction of CuFeS2 reacted at time t, pB is the molar density of CuFeS2, do is the initial diameter of the particle, e is the electronic charge, s is the total electrical conductivity of the sulfur layer, and ?G is the Gibbs free energy for the reaction:

Jan 1, 1984

By J. P. H. Steele, T. Vincent, C. Debrunner, M. Whitehorn

For a variety of reasons, the need for automation of underground mining equipment is growing dramatically, e.g., improved safety and health, availability of labor, deeper mines, and desire for more focused excavation. While there has been tremendous progress made in this direction, much needs to be done to reach the holy grail of an autonomous mining machine. This paper reviews a number of technological developments and presents research and development needs for future development. A report on our current project for the Western Mining Resource Center at CSM is included.

Jan 1, 2000

By Frederick B. Brien

For many years tin mining in Bolivia has been very important to the economy of the country. In recent years the tin content of the ore reserves has been steadily declining. An improvement in concentration efficiency is highly desirable in order to increase productivity from the present-low-grade mine ores and to allow retreatment of the many millions of tons of tailings from past operations, some of which equal the present ores in tin content. A number of investigators have been or at present are working on various phases or approaches to the problem. Gravity concentration is used in Bolivia today as it has been in the past to recover tin minerals from the mine ores. An objective of the work reported in this paper was to examine the possibility of treating present low-grade ores and sink-float tailings products, at a relatively coarse grind, in order to produce a higher grade feed material to the present gravity concentration plants. The possibility of using heavy liquids in cyclones to treat large tonnages with a minimum of outlay presented itself and is of particular interest since appropriate heavy liquids are available and with physical properties which lend themselves to simple recovery methods. Tests were carried out using a closed circuit laboratory cyclone assembly. It was desirable to determine the value of using the SG50 concept and Tromp curves for analyzing the cyclone concentration test results. The effects of entrained water on the behavior of ore particles in the cyclone were examined.

Jan 1, 1964

By Jr. Babcock

The Pyke asbestos deposits were discovered by Kennecott Explorations (Australia) Pty. Ltd., in 1969 during the course of base metal exploration on the South Island of New Zealand. Extensive occurrences of chrysotile asbestos were found associated with the Red Mountain Ultramafics in the headwaters of the Pyke River, and to the north and south along the ultramafic belt for a distance of 70 kilometers. Surface evaluation and drilling by Kennecott in 1970 and 1971 identified numerous small deposits of good grade fibre in the Little Red Hills between the Pyke and Barrier Rivers. Additional drilling and three adits have been completed by other companies since that time. The property is presently held by Lime and Marble, Ltd. Of Nelson, New Zealand, and Kennecott Explorations (Australia) Pty. Ltd. This paper will present the regional and local setting of the asbestos deposits, including the geology and nature of mineralization. In addition, the exploration methods used by Kennecott in the discovery and evaluation of these deposits will be outlined. Subsequent work by other companies will be mentioned, but not described in any detail. This subsequent work did not alter Kennecott's conclusions or produce any serious changes in the interpretation of geology and mineralization. The author acknowledges the contribution of the many employees of Kennecott Explorations (Australia) Pty. Ltd., who have been involved in the project, particularly Ramon Farmer, N. G. Comer, and A. W. McConie, who were responsible for completion of field work and reporting on the project. The responsibility for the conclusions and interpretations of this report are solely that of the author and result from his involvement in discovery of the deposits and management of the exploration program.

Jan 1, 1978

By Meng Li, Hao Nie, Weitian Ding, Mamdouh Omran, Ying Li, Yao Ge, Yaowei Yu, Abourehab Hammam, Lei Zan

This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H2 atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H2 is more efficient thanwith CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H2 gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H2 atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H2 atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion.

Sep 29, 2020

By Omid Asghari, Amin Mousavi, Arshad Ranjbar

Geometallurgical modeling of the production benches is an attempt to estimate the geometallurgical variables of the different ore domains, which leads to a better understanding of the ore and its properties. Having geometallurgical variables results in a more accurate prediction of ore characteristics, an improved drilling and blasting operation, and better efficiency of the processing plant. In this research, the geometallurgical variables required for the geometallurgical modeling of the extraction benches are discussed. Then, the relations between Bond work index (BWi), as one of the most important geometallurgical variables and the primary grindability index, and rock geomechanical properties are investigated based on the previously published studies. The BWi is the main parameter for measuring the resistance to the grinding of ore minerals. It represents the energy required for processing (e.g., crushing, grinding) ore rocks in the beneficiation plant. As a real case study, BWi of a production bench in Sungun Copper Mine, located in East Azarbaijan province, Iran, was estimated. The rock’s geomechanical properties were measured using laboratory tests, including uniaxial compressive strength, Brazilian tensile strength, point load strength, and hardness. Then, BWi was estimated using the proposed formulas in the literature and the results of the rock’s geomechanical properties. The selected bench consists of three ore zones and two dyke domains. The laboratory tests revealed that the first ore zone has a slightly higher compressive strength than the other two zones, while the compressive strength of the waste rocks is larger than the ore domains. Using the proposed equations in the literature, the predicted values of the BWi for the samples in ore zones are in the range of 6.36 – 14.44 (kWh/t), and therefore this wide range must be considered when the short-term production schedule is planned. In addition, variations are observed in the samples within a specific zone and between the ore zones, demonstrating heterogeneity in the selected bench. Finally, wide-open results obtained by different equations show a necessity to perform a geometallurgical program specifically for the Sungun mine.

Oct 28, 2021

By E. J. Garrison

A.C. Noble presents a clear and concise summary of the factors pertinent to a competent reserve evaluation of a mineral occurrence. However, I believe that he confuses the difference between a resource and a reserve. By definition, a reserve estimate includes all known economic, legal, mining, metallurgical and environmental factors impacting the recovery of the product(s) found in the deposit. A resource estimate, however, is an estimate of what is there - what is available for exploitation and should not include economic and other considerations. Only after defining the resource, its extent, location, physical and chemical properties, can an intelligent selection process begin of the extraction and processing technologies most appropriate to the circumstances encountered. The early and almost certainly inappropriate application of these often cookbook choices has probably lead many companies to walk away from good properties. (How many mines have been found in others rejects?) An example of the process is the early selection of metallurgical samples, after encouraging values are found in a few holes or surface samples, in an attempt to determine the economics of the prospect. Unfortunately, the sampler does not know how representative of the occurrence the sample is because he does not know what the deposit looks like. As a consequence, the property becomes saddled with a bad metallurgical sample that is often inappropriately used in evaluating the deposit which it does not represent.

Jan 1, 1994