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By C. L. Lin

A PC image-based, on-line instrument for the measurement of coarse particle size on a conveyor belt is under development. Both the hardware and software required to implement such a system are discussed, including the interface for the special image acquisition hardware. The system concept is given with examples to illustrate the step-by-step procedure for the implementation of image-processing algorithms.

Jan 1, 1992

When exploration shows a mineral deposit to be of importance, the subsequent work of defining the limits or boundaries of the ore body and preparing it for the extraction of the mineral is termed development (Young, 1946). In underground mining, development also connotes the work that is involved in opening up a deposit preparatory to stoping or productive operations. In this section, mine development is defined to include all studies and operations that will enable a sound evaluation of an explored ore body from the technical and financial standpoints. Though the ultimate objective of all mine development activities is the same, the scope and detail of these activities vary depending on the type of ore body (e.g., flat bodies, lenses and sheets, massive deposits, narrow veins, and bedded deposits), and the method of working the deposit (e.g., under- ground or surface methods or a combination of both of the methods). Therefore, the various contributions in section 3 address such topics as long-range planning, feasibility studies, and valuation for many types of ore bodies and different mining methods. This introductory review is divided into three major parts. In the first part, long-range planning aspects are briefly discussed with .an emphasis on current trends that affect mine planning. In the second part, an overview is provided of the contents in the mine development and valuation section. In the last part, remarks are made on the status, scope, and future of quantitative and computer methods in mine planning and development.

Jan 1, 1979

[University of Alabama University, Alabama Mining and Metallurgical Society (Inactive) University of Arizona Tucson, Arizona Miners' Society ROBERT HIGH, President RICHARD FLAGG, Secretary J. B. CUNNINGHAM, Faculty Sponsor Birmingham-Southern College Birmingham, Alabama Geology Journal Club (Inactive)]

Jan 1, 1946

I should like to congratulate Dr. Salamy on his most informative paper.Under the heading of "future development" Dr. Salamy states the intention of using 3 in. lifters. In this connection I should like to mention one or two of our findings at the Croesus Plant of North Kalgurli (1912) Limited. We have converted a 5i ft. x 11 ft. grate discharge ball mill to a high level overflow rod mill. When we were considering this conversion we explored the literature and decided on using 2t in. lifters on alternate liners-the results were not encouraging. The mill all but "took off" from its foundations,and performance with regard to tonnage was poor. There...

Jan 1, 1956

By G. R. Tostengard

Gold plant performance during the start-up period, which extends until capacity production is sustained, has a major impact on the internal rate of return and the net present value of gold projects regardless of mining and processing configurations. The start-up period experiences substandard production, extra expenses, and sometimes reduced recovery. This results in lost profits, a portion of which are recouped at the end of the life of the mine. Poor start-up performance can put projects into financial jeopardy. The gold mining industry regularly experiences start-ups ranging from good to poor. Problem areas, which affect start-up performance, include shortcomings in ore reserve sampling and testing, equipment design and installation, untrained plant operators, inability to cope with problems which arise, and organization of the maintenance program. An investment, equal to 0.5% to 1.0% of plant capital cost, in programs to prepare for start-up, in advance, is recommended. Investment in such a program will make a good start-up possible. Without it the best result which can normally be expected is a fair start-up. Developers of new gold mines are urged to compare the cost of this investment with the anticipated increase in project net present value. Funds for this investment should be included in feasibility studies.

Jan 1, 1988

By Behrouz Ohadi, Kamran Esmaeili, Bibhu Mohanty

In most metalliferrous open pit mines with heterogeneous orebodies, blast-induced rock movement is a crucial outcome that has unfavorable impact on ore and waste segregation in the post-blast muck pile, resulting in either ore loss (the ore is misclassified as waste and sent to the waste rock dump) and/or ore dilution (waste is misclassified as ore and sent to the processing plant). While many studies have been carried out to assess the influence of blast design parameters on blast-induced rock movement, the influence of rock mass characteristics in these studies have been overlooked.

Jan 1, 2018

By H. G. Fleshman

Thousands of years ago, Chinese water well drillers developed a technique for punching holes in the ground by lifting massive metal bits and letting them fall against the rock. With diligence, they could pound away about 2 feet a day. The Chinese drillers pounded holes in the ground this way for almost 2000 years. In the 1860's, French water well drillers developed a perforated bit moistened by fluids pumped into the hole through a hollow rod. The fluids carried the cuttings from the hole and spared the Frenchmen the task of bailing them out by hand.

Jan 1, 1986

By George V. Smith, Daniel E. Sonon

Various mechanical properties of the Ni-Co-C alloy system were investigated to delineate the strengthening effect of carbon. Carbon concentration, cobalt concentration, vain size, temperature, and strain rate were varied so that thermal activation analysis and the Hall-Petch analysis could be used to evaluate the strengthening effect of carbon. Increasing carbon increased the strength of nickel and a Ni-60 pct Co alloy , with the effect becoming more pronounced at lower temperatures. Yield stress depended linearly on carbon concentration in nickel, but it depended on the square root of carbon concentration in the Ni-60 pct Co alloy. The Hall-Petch slope of nickel increased with carbon concentration; however, that of the Ni-60 pct Co alloy did not. The yielding behavior of these alloys was sensitive to composition, grain size, and temperature. Cobalt eliminated serrations in the flow curve of carbon-containing nickel at 300' and weakened them severely at higher temperatures. Pairs, or clusters, of carbon atoms appear to be responsible for the observed strengthening behavior. FLINN' conducted several experiments with carbon in nickel in an effort to provide information on the strengthening effect of interstitial impurities in solid solution in fcc metals and alloys. Strengthening which increased with decreasing temperature led him to conclude that carbon causes Cottrell locking in nickel. Fleischer2 analyzed Flinn's data and calculated that the strengthening effect of carbon in nickel was smaller by a factor of fifty than the strengthening effect of carbon in a! iron. Fleischer2 termed the magnitude of strengthening of carbon in nickel "gradual" and that of carbon in a! iron "rapid". He attributed "gradual" hardening to hydrostatic strains and localized changes in modulus of elasticity around solute atoms, whereas he attributed "rapid" hardening to tetragonal strains around solute atoms. Sukhovarov et a1.3-7 reported strain aging and serrated plastic flow in nickel, both of which they attributed to the presence of carbon. Serrated plastic flow has been rationalized by a process involving a series of dislocation pinning and multiplication steps.8, This process is more probable when screw dislocations are strongly pinned. Screw dislocations cannot be pinned by pure hydrostatic forces from the symmetrical strains of an interstitial impurity in an fcc lattice, except for small, second-order effects. However, they might be pinned by localized changes in modulus of elasticity around solute atoms,' by the pinning of the edge components of the partial dislocations of an extended screw dislo~ation,'~ or by clustered groups of solute atoms whose net elastic stress field is unsymmetric. The purpose of the present work was to investigate various mechanical properties of the Ni-Co-C a1loy system which are sensitive to pinning effects in order to delineate the specific pinning mechanism of carbon. Carbon concentration, grain size, temperature, and strain rate were varied so that thermal-activation analysis and the Hall-Petch analysis could be used to evaluate the pinning mechanism. Cobalt was added to lower stacking fault energy so that the number and extension of split, screw dislocations would be increased in order to test the possibility of pinning by carbon at extended screw dislocations. EXPERIMENTAL PROCEDURE Nickel and cobalt (both 99.98 pct-. pure) were melted with graphite in stabilized zirconia crucibles and cast at lo-' Torr to form Ni-C and Ni-60 pctCo-C alloys. Two ingots were heated to 1250°C and were forged to 1-in.-sq bars. These bars were machined to 4-in.-round bars, and then swaged cold to 0.144-in. -diam rods. Reductions in area of approximately 75pct were used with intermediate anneals at 900°C for 1 hr. The carbon content of batches of 0.144-in.-diam rods from each ingot was reduced to two levels by annealing 5-in. lengths in palladium-purified, dry hydrogen at 1100°C for 25 and 100 hr. The remaining material from each ingot was annealed at 10"5 Torr for 1 hr at 1100"~. These treatments gave a total of three carbon levels for both the nickel and the Ni-60 pct Co alloy. The 0.144-in.-diam rods were swaged to 70-mil wire, cut into test specimens, and then re crystallized at lom5 Torr in capsules for 1 hr at temperatures ranging from 760" to 1050" ~. The capsules were broken and the specimens were immediately quenched into water. Average grain size was measured using Hilliard's method of circular intercepts." Annealing twin boundary intercepts were counted in addition to grain boundary intercepts to establish an average grain size. Average grain sizes ranged from 5 to 140 p depending on the cobalt concentration and re-crystallization temperature. Tension tests were made in duplicate at various temperatures at a crosshead speed of 8.34 x 10"4 in. per sec with an Instron Universal Testing Machine. Specimens of 1-in. gage length with soldered ball ends were used at atmospheric and cryogenic temperatures. Pinch grips were used on specimens at elevated tem-

Jan 1, 1969

By J. Y. Hwang

The relationship between coal characterization and physical cleaning has not been well understood due to the complex nature of coal. Therefore, it is difficult to apply the results of coal characterization to predict and evaluate the performance of a physical separation (e.g. flotation). Eight U.S. bituminous coals were analyzed and studied petrographically in conjunction with washability and flotation tests. The results show that grindability correlates to ash and fixed carbon contents; liberation determined directly by petrographic techniques is close to liberation determined indirectly by washability; and an ideal separation efficiency can be determined by measuring the inertinite content and the washability separation efficiency using a heavy liquid with a density of 1.4. The ideal separation efficiency was attained for most coals by packed column flotation. The ideal separation efficiency can be used for comparing process technologies and process parameters.

Jan 1, 1988

By A. Nicotra, E. H. Roux, J. H. du Plooy, D. H. de Jagger, P. De Waal, G. J. van der Linde

This paper reviews the geology, history, current beneficiation practices, uses, marketing, and future outlook of phosphate in South Africa. The vastness of the reserves, and the industry's efficiency and competitiveness in world terms, are highlighted.

Jan 1, 1989

Arguably the SMC Test® has become the most popular laboratory hardness test in the world with over 17,000 tests having been completed to date, covering over 650 different ore bodies. It is now routinely used in design, optimisation and orebody profiling projects. The test is unique in that from relatively small amounts of drill core it simultaneously provides parameters that are used in simulation modelling of AG/SAG and crushing circuits as well as work indices that are used in power-based equations for predicting the specific energies of AG/SAG/Crushing and HPGR circuits. The very large data base that has been accumulated has provided the opportunity to study the differences in variability from deposit to deposit. This paper describes and discusses the trends that have become apparent from the study of this data base. Recommendations for appropriate selection of sample numbers are also made which are based on these trends.

Jan 1, 2012

By R. F. Favreau, P. Favreau

Rock excavation is the first process in the cycle of operation of a mine, and efficient blasting is paramount to the profitability of the mine. The traditional way to design blasts has been by trial and error, based on the experience of the designer. This is probably the only important engineering practice which continues to be done without a precise engineering technique. The efficiency of most other mine processes has been improved by the use of high-tech, while a majority of blast design has not yet profited from the advantages of the computer. However, with the advent of the high-tech blast simulator Blaspa, it has become possible to design the parameters of the blast according to normal engineering practices. Over the last 50 years, the chemical and physical mechanisms which occur during a blast have come to be identified; they are reviewed in section B. Although these mechanisms are complex, they have nevertheless been expressed in terms of mathematical equations which have been assembled together in the computer to create the blast model Blaspa.

Jan 1, 2002

By Chris M. Healey

"Abstract- The Jasper Gold mine in northern Saskatchewan produced a total mill feed of 140 127 tonnes at an average grade of 19.0 g/t Au. Both diamond drilling and chip samples from under­ ground workings returned extremely high values, up to 12 851 g/t (375 oz/I) Au over 0.10 meter from a chip sample. In the presence of such extremely high grades, the accurate estimation of reserves is a major problem.ln the first part of this study, production data from the mine were used to evaluate the results of a variety of reserve estimation techniques in this environment. In two out of three cases studied, indicator kriging with assays cut to 342.9 g/t (10 oz/I) gave extremely good results. In the third case, however , indicator kriging gave unacceptable results. Instead, lognormal kriging of uncut data gave the best results.Secondly, from the same database, a number of drill-hole spacings were simulated, and reserves estimated from the simulations. As may be expected, the results of this analysis show increasingly better results with tighter drill-hole spacing. However, even with a 5 m by 5 m spacing the variation from actual grade was quite large. This is not a systematic under- or over-estimation of grade, rather a random scatter of results .The results of this study show very clearly the problems of deriving good estimates of reserves when extremely high-grade samples are encountered. There is a high degree of randomness to this database, so reserve estimation in this situation will remain a high-risk operation."

Jan 1, 1993

By Mark Sherman

One of the main functions of a process technology and engineering services provider is to select grinding equipment that will meet the client?s throughput rate target. Prudent risk mitigation strategies would suggest that throughput rate estimates be cross-checked using a variety of techniques. Whilst some comminution circuit designers have estimated specific energy requirements via the manipulation of the Bond specific power equation e.g. Barratt?s Grindpower and OMC?s FSAG approach, other designers have opined that the Bond Indices have no role to play in the calculation of SAG mill specific power. As a result, they have developed their own specific energy estimating methodologies, e.g. SMCC?s Drop Weight based power methodology, SPI, SAGDesign, etc. Each method has its supporters and its critics. The challenge facing the engineering provider is how to nominate an SAG mill based circuit throughput rate estimate when faced with significantly disparate specific energies calculated by the different methodologies. This challenge is exacerbated via the continuing evolution of contemporary circuit configurations such as two stage pebble crushing some of which incorporate HPGR technology as the second stage of pebble crushing. The methodology presented in this paper shows that the Bond Indices are an excellent tool for estimating the specific energy requirements for SAG mills in SAB, SABC and SSS circuits. The method accommodates primary crushed feeds, partial and or fully secondary crushed SAG mill feeds, and emulates the impact of pebble crushing on SAG specific energy. As a result, the new Bond Index based method has provided an additional tool for increasing Fluor?s confidence when predicting SAG mill based circuit throughput rates. Based on this outcome, the author proposes that the decades old conundrum of using Bond Indices to calculate SAG specific energies for SAG mill based circuits has been solved.

Jan 1, 2012

By David W. Zeeb

The use of an ordinary VHS video camera and a four-head player can be an effective tool to analyze surface blasting. The necessary equipment can be purchased for under $1,300 and will allow frame by frame or slow motion viewing of a blast in 33.33 millisecond increments. Rock breakage, movement, and timing can be studied in high quality slow motion. These studies can result in improved blasts by showing things that the eye can miss in real time.

Jan 1, 1992

By Y. Mitani, H. Ikemi, K. Kitamura, H. Honda

"Instead of carbon capture and geological storage (CCS) that does not rely on structural aquifers, injecting carbon dioxide into sedimentary rock deep underground has been considered. For advection velocity of the fluid is slow, the permeability of sedimentary rock deep underground is low. In order to perform the CCS on the low permeable sedimentary rock, it is necessary to clarify the behavior of long term storage properties of carbon dioxide (CO2).In this study, the permeability and storativity of CO2 injected into low permeable rock has been evaluated. The injection of supercritical CO2 has been conducted on the specimen of Ainoura sandstone (unit weight: 2.39 g/cm3, porosity: 11.9 %) saturated with water by using flow pump method. The experiment has been set up to reproduce the similar condition of deep underground reservoir under 20 MPa confining pressure, 10 MPa pore pressure, 35°C temperature and 3 µl/min CO2 injection rate. In order to prevent an increase in pore pressure, the boundary condition on the outlet side of specimen has been kept a constant pressure.As a result, it has been possible to observe step by step the change of the differential pressure between both ends of specimen. Furthermore, the relative permeability and specific storage of rock under supercritical CO2 injection has been examined by the theoretical analysis of flow pump permeability test incorporating Darcy’s law for two-phase flow. It is observed that CO2 has been transmitted gradually while CO2 stored in the rock. It is also clarified that residual water has existed in specimen after showing the constant differential pressure in the end of the experiment. Using the results of the experiment, 3D core-scale flow-simulation by using TOUGH2 has been conducted due to confirm the flow of fluid and CO2 distribution in the specimen. From the experimental results and analytical solution to them, permeability and storativity are identified, and simulation results support the validity of the experimental results."

Jan 1, 2015

By Robert S. Schecter, Paul M. Bommer

This paper presents the development of and results from a computer model of in situ uranium leaching. This model uses a streamline-concentration balance approach and is useful with a wide range of reservoirs. It can be used with any type of well system, in a reservoir with or without boundaries, and with any form of descriptive kinetics. The model also includes the effects of dispersion and consumption of oxidant by minerals other than uranium. The effects of areal sweep, variable uranium concentrations, variable permeability, and the presence of oxidant consumers on uranium production are shown and discussed.

Jan 1, 1979

By J. H. East, D. Harrington

"INTRODUCTION Burning refuse dumps are a common and by no means pleasant sight in most coal-mining distracts; they have been and largely continue to be accepted as a necessary, if undesirable, adjunct to coal-mining operations. The odor, smoke, and fumes emanating from the burning dumps have caused much property damage, as well as aroused unfavorable public sentiment in the areas thus affected; and there is reason to believe that, in at least some cases, they have had an adverse effect on the health of certain communities, adjacent to mines. In some instances such communities have been owned or controlled by the mining companies and in others they are incorporated towns.After the start of World War II, it was necessary for Great Britain to take prompt and effective measures to extinguish or at least blanket the burning refuse dumps at collieries, since the fires served as beacons for the enemy planes; the problem thus became a matter of national security rather than one of local inconvenience. If the United States should become involved in a bombing war, these dumps might became a source of national danger, hence now is a propitious time to at least make a start on available methods of solving this problem. Much progress was made in Great Britain in extinguishing the dump fires that had burned for years and in preventing newly made dumps from taking fire.Burning refuse dumps have not been a national problem in the United States, but they are a nuisance and frequently a danger and often a fruitful cause of poor public relations on account of the odor and fumes. Many progressive coal-mining companies are taking effective and positive action in trying to extinguish old dump fires and to build new dumps so they are less likely to fire.The purpose of this paper is to provide information about the problem as well as on ways to extinguish refuse dump fires, to describe methods of constructing dumps that probably will prevent them from firing, and to point out some of the danger that exists when dumps are improperly built and when they are on fire."

Mar 1, 1948

The face of project evaluation is changing continuously, making it ever more critical to get a clear understanding upfront of the objectives, decision-making processes and criteria of the project proponents. Requirements are usually significantly different for emerging æjuniorsÆ compared with long established major mining houses and companies in developing countries compared with western companies. Requirements are also different for different types of evaluations, such as due diligence studies compared with feasibility studies of æownedÆ projects and there are often key misunderstandings around the use of the term æbankableÆ. Further, it has become increasingly important with increasingly remote and lower quality resources to understand risk relativities such as infrastructure compared with the core processing facilities. This has also driven the need for more trade-off studies to determine the best balance between critical issues, such as optimisation of the interface between mine and processing plant, capital versus operating cost and automation versus labour. In every project evaluation, it is also critical to consider emerging trends and changing requirements and standards such as sustainability and community interface. Finally, the inescapable drive to reduce time to market has driven changes such as increased use of more standardised designs and innovative approaches to the transition from project development to execution. This paper begins with a brief review of the different objectives and risks of each project development stage to establish a framework for subsequent discussion of the different requirements of different types of companies in different locations, different types of evaluations and different types of projects and project components. This is followed by a review of changing requirements and standards and some innovative developments in sustainability and community interface are presented. Finally, the paper outlines a number of developments in the area of operational readiness planning that focus on minimising the time to achieve maximum return on investment.

Jan 1, 2009

By Raja V. Ramani

In many instances, the actual production from a longwall face does not equal the planned capacity. General problem areas which have been identified include face length and panel depth, face area and gate entry roof support, face conveyor and shearer wear, outby haulage system failures, number of entries in longwall gate development and longwall move time. The performance of a longwall face is totally dependent on the interaction of these and many other factors. To explore fully these interactions, a systems analysis of longwalls has been performed. In this paper, the systems approach, the factors considered in the analysis, and the results of the analysis are presented.

Jan 1, 1983