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By Ron Stewart, Richard Youmaran, Andy Adler

In the current context of heightened concerns with explosives security, there is significant interest in technological controls to improve security. It is important to be able to control what is fired, by whom, where and when. This paper describes research Orica has performed to investigate and test biometric systems to address the question of "by whom". The goal of this research is to incorporate the most suitable biometric system onto the 'blaster' unit of an electronic initiation system. This approach will ensure that only authorized personnel can initiate a blast involving electronic detonators. Requirements analysis: we initially explored many different biometric technologies to evaluate them against the requirements, including security, usability, ruggedness, size, form factor, privacy, and operational temperature range, This analysis identified chip based fingerprint sensors as the best candidate. Development of prototype units: in order to test the identified sensors, we modified standard, commercially-available, electronic blast initiation units ("blaster") to incorporate a fingerprint reader. Testing and evaluation: Biometric We conducted a biometric scenario evaluation in order to determine: 1) security level (measured by false accept rate (FAR)); 2) usability (measured by failure to enroll (FTE) and false reject rates (FRR)), and to 3) discover environment specific issues and challenges (such as temperature, humidity, dirt, or those related to the usage patterns of the user group). Tests were conducted at quarry sites in eastern Ontario, Canada. Results show rates of: FAR= 0%, FTE= 1.67%, FRR= 28.81%. Overall, these results suggest that this fingerprint biometric technology has a good level of usability in this application of electronic blast initiation control.

Jan 1, 2007

Central to any business is its Asset Management Plan which encapsulates the business context and key organisational objectives such as profitability, safety and environmental standards. Life Cycle Planning (LCP) is a key component of an overall Asset Management Plan. A comprehensive approach to Life Cycle Planning forecasts the financial expenditure required to support the performance of the asset over the business life. It incorporates capital, maintenance and operational expenditure along with an estimation of economic life. Within its body the LCP provides the detail of the maintenance plan and method of its execution. Once optimised the LCP becomes the overarching plan executed through the application of several elements of the Asset Management Plan to ensure the return on investment from the assets is optimal. Each of the elements of the LCP is bound by a set of loops that provide information based on the analysis of outcomes. These loops drive the continuous improvement of performance and cost over the life of the asset. In this way we ensure that the LCP is a dynamic plan responsive to the changing business environment. The paper being presented today will describe the process undertaken and the outcomes derived when this approach was applied to a $600 M+ coal handling and preparation plant in QueenslandÆs Bowen Basin. It will also delve into the difficulties encountered from both technical and cultural aspects; the latter proving to be the most difficult to manage. It will describe the hurdles and barriers that hampered progress including the human influences and the natural desire to revert to what has been done in the past when things became a bit difficult. In the end the results are there to show that the upfront expenditure and investment in time was time and money well spent and the outcome has the operation well placed to manage the assets in a manner designed to deliver the optimal business outcome.

Jan 1, 2007

By L. S. Linda, P. G. H Pistorius

Ferritic stainless steel is utilized to fabricate automotive exhaust systems using a ferritic weld metal. Ductility of the weld metal is higher if its microstructure contains a significant proportion of equiaxed grains. The formation of equiaxed (rather than columnar) grains is favoured by a higher titanium weld metal content. In this study, the Ti content of ferritic stainless steel weld metal was changed by using Tifree (Type 436) and Ti-containing (441) ferritic stainless steel as base metals. The metal-cored welding consumable contained 0.4% Ti. Gas–tungsten arc welding and gas–metal arc welding processes were compared. The weld metal Ti content ranged from zero to 0.5% Ti, as determined from scanning electron microscopy supplemented by inductively coupled plasma optical emission spectroscopy. Cross-sections of the weld beads were subjected to point counting (to estimate the fraction of equiaxed grains) and image analysis (to estimate the average grain size). Point counting proved to be more reliable. The fraction of equiaxed grains was sensitive to the Ti content, but not to the welding process. Below 0.4% Ti, the fraction of equiaxed grains gradually increased with an increase in the weld metal Ti content; above 0.4% Ti, the fraction of equiaxed grains rapidly increased with increasing Ti content. The transition in behaviour at 0.4% Ti corresponded to a Ti content at which Ti-rich precipitates became stable at the estimated liquidus temperature of the weld metal.

Jul 2, 2022

By Sabry A. Sabour

Metal price is among the key variables in the open pit optimization and the economic evaluation process. The common approach to handle metal prices in open pit mine planning is to optimize the ultimate pit and the mining schedules using a fixed, flat metal price. In this respect, metal price is assumed to be known with certainty throughout the entire mine life, which in some cases can reach 80 years. Given the volatile nature of metal markets and the metal price cycles, the conventional pit optimization approach may generate sub-optimized mining plans, which results in either extra costs to mining projects or lost revenues, or both. Long-term operational decisions such as future pit expansions, beyond the currently optimized limits, cannot be handled using the pit optimization approach based on flat metal prices. There is a growing interest in the mining industry to model and manage such market uncertainty in the pit optimization as well as the project evaluations in order to maximize the value of mining operations. In this paper, the author will outline a practical approach to optimize the ultimate pit taking into account the volatility and variability of metal markets. The proposed approach uses a combination of the pit optimizer of the commercial MineSight package and a simulation-based economic modeling real options valuation approach employing the least-squares Monte Carlo algorithm. MineSight pit optimizer employs both the floating cone for initial optimization exercise and the standard Lerchs-Grossmann algorithm. In this paper, Lerchs-Grossmann option will be used to generate the pit shells. Real options valuation approach used in this study is based on generating multiple metal price scenarios. Metal price uncertainty is modeled using stochastic metal price models such as the geometric Brownian motion and the mean-reverting process. The mining operational scenarios corresponding to the simulated metal prices are then optimized using the least-square Monte Carlo approach. The objective is to maximize the discounted cash flow value of the project while incorporating the operating flexibility to revise the operating status of the open pit with time as new information becomes available. The focus of this work is on the practicality of the proposed uncertainty-based pit optimization approach and the difference it can make to the technical operational mining decisions. A case study of a hypothetical open pit poly-metallic mine is provided. The deposit contains copper, gold and silver grades. The run of mine ore is sent to the process plant that produces copper concentrate with copper as the main metal and gold and silver as the by-products. Four uncertain variables are considered here include copper, gold, silver prices and foreign exchange rate. Both copper price and exchange rate are modeled using the mean-reverting process while gold and silver prices are modeled using the geometric Brownian motion. The case study is performed using both the conventional flat price pit optimization approach and the proposed uncertainty-based one to compare results.

Aug 1, 2013

By R. A. Thomas, C. D. Litton

"The objective of this study was to develop a laboratory-scale method to rank the ignition and fire hazards of commonly used underground mine materials and to eliminate the need for expensive large-scale tests that are currently being used. A radiant panel apparatus was used to determine the relevant thermal characteristics of the materials: time to ignition, critical heat flux for ignition, heat of gasification, and mass loss rate. Three thermal parameters, TRP, TP1, and TP4, were derived from the data, then were developed and subsequently used to rank the combined ignition and fire hazards of the combustible materials from low hazard to high hazard. The results compared favorably with thermal and ignition hazards of similar materials reported in the literature and represent a simpler approach to quantifying these combustible hazards. INTRODUCTION The potential fire hazard from combustible mine materials is a major concern that can impact the safety of mine workers. Combustible materials tend to be solids and within this category there exist degrees of flammability and fire resistance. These materials may be readily ignitable or they may be able to withstand high temperatures and high heat fluxes. Presently, no simple methodology exists to assess these possible fire behaviors and quantify the resultant fire hazards. Thus, better knowledge of the thermal properties and chemical characteristics of combustible materials is of great importance to the safety of mine workers. Tewarson [1994] developed a methodology which he subsequently used to evaluate the ignition and fire resistant properties of combustible mine materials, but these efforts are more than 20 years old, and do not include many of the new materials used in mines today. The standard practice that has evolved for a combustible material to be approved by the Mine Safety and Health Administration for use in underground coal mines is to conduct extensive and costly large-scale experiments on each new material that is used in a particular mine operation. Results of such tests provide pass/fail answers to the questions of a material’s flammability or fire resistance, yet they provide little, if any, information that will lead to a better understanding of the basic mechanisms involved. Therefore, there is a need to quantify material flammability properties and to develop a methodology to rank the ignition and fire hazards of commonly used underground mine materials. During the heating and ignition stages of combustible materials, properties such as smolder susceptibility, minimum surface temperature for ignition, thermal conductivity, heat capacity, density, and heat of gasification are known to be important [Apte, 2006]. During the flaming stage, additional parameters, such as the heat of combustion, heat release rate, flame spread rate, yields of soot/smoke, and toxic gas production become more important as the flame is sustained and spreads. In very general terms, the heat flux incident on the surface of a solid combustible not only controls the rate of temperature increase of the local fuel surfaces, resulting in expulsion of fuel vapors that sustain the flaming process, but also the heating of other combustible surfaces that subsequently ignite and spread flame."

Jan 1, 2015

By The Staff

This is in direct contradiction to the generally accepted philosophy of tube-mill grinding, which is based upon an enormous amount of experiment carried on in different parts of the world. Personally, I have no faith in the reliability of these conclusions of the authors. (Incidentally, the two circuits compared consist of six mills each of which the change in the hook-up is only in the last three mills-in one case, these three mills are in closed circuit and in the other, open or series circuit. Hence the last three mills are alone responsible for the alleged improvement, which means that the improvement in these three mills amounts to at least 18.8 per cent). The value of these figures depends upon the reliability of the work, of the measurements and the calculations of the authors. As very little information is contained in this Addendum concerning the methods of the work and the details of the measurements, it is necessary, in order to form an estimate of this reliability, to study carefully the previous paper published in the July, 1940, BULLETIN(3). Referring to the original paper, the present paper has this to say (bottom of page 379): "Here it may be remarked that we have made more money for Lake Shore digging into and forming the report than in obtaining the figures and data, and so far have never gone back to work on it without a resulting Lake Shore profit". Let me state that I, so far, have never gone back to work on it without finding more discrepancies and inconsistencies and illogical reasoning. In my first contribution to the discussion of the first paper, which discussion was published on page 355 and following, in the July, 1941, BULLETIN, I pointed out discrepancies and inconsistencies and illogical reasoning.

Jan 1, 1942

By D A. Sketchley

The Merlin Zone, a 2008 high-grade Mo-Re discovery, is a part of the Mount Dore Deposit in the Eastern Succession of the Mount Isa Inlier in Queensland, Australia. Hosted by carbonaceous metapelites and phyllites, the Merlin mineralisation comprises molybdenite veins, breccia infillings, stylolitic fracture fillings, and disseminations. Because rhenium is geochemically similar to molybdenum and commonly associated with it, global production of rhenium has been mostly a by-product of molybdenum refining. The high-grade rhenium in the Merlin Zone is an exciting discovery that is expected to become a direct source of rhenium. At the time of discovery, quality assurance (QA) procedures for rhenium were not in place at the Merlin Zone; therefore, they needed to be developed.The Merlin Zone was discovered using reverse circulation drilling, which led to concerns about molybdenite loss due to poor sample recovery. The twinning of the discovery hole with diamond core demonstrated a two-fold increase in molybdenum grade over several tens of metres. Consequently, the resources of the Merlin Zone were defined using assays from diamond drill core.Early analytical work, which was initially done only for molybdenum, comprised geochemical analysis with an aqua regia digestion, which have poor precision and can be biased low. Although initial testing for rhenium used similar procedures to those for molybdenum, a scarcity of commercial rhenium reference materials led to a validation process using neutron activation analyses and different digestions. This resulted in introduction of four-acid digestion assays, development of matrix-matched reference materials, and improvements to the quality of molybdenum and rhenium assays for reporting resources. Coarse and pulp duplicates were used to check for sampling bias and to ensure that levels of precision were adequate for the style of mineralisation and analytical methods. In addition, the direct and consistent geochemical correlation between molybdenum and rhenium provided another method for checking analyses.

Aug 22, 2011

By C. O. Swanson

CALCULATING the average grade of a gold deposit is a problem that presents certain unique difficulties. Particularly troublesome is the fact that the average of the samples taken from a deposit is likely to be higher than the grade of the ore that is eventually mined, even when allowance is made for dilution and other factors resulting from the mining operations. It would seem that this situation is due to the presence in the deposits of structural peculiarities which have not been properly taken into account, since estimating the average grade of the broken ore produced from the deposits does not present the same difficulty. It is therefore evident that structural considerations are of prime importance in estimating the grade of a deposit. This fact is clearly realized and taken into account in cases where the boundaries of the orebodies and the variations within them are easily recognized. But in many gold deposits this condition is not satisfied, a circumstance which can be regarded as the main source of difficulty. Lacking definite information concerning the structure, we are apt to use certain procedures which are either empirical or based on general probabilities.

Jan 1, 1945

By Gerd Weyand

Gontermann-Peipers GmbH (GP) Germany developed a new, high alloyed steel grade for the manufacturing of back-up rolls. The advanced GP double pour casting processes provide highest flexibility in being quite open in rolls work layer chemistry and hence microstructure with no influence on core respectively neck properties. GP took the process advantage to provide a brand new back-up roll grade with remarkably reduced roll wear while operating with textured work rolls. In the meantime several successful trials have been made with this new roll grade on different Skin Pass Mills. As a result the performance of back-up roll and thus availability of mill will be improved while specific costs for mill will drop. This quite new back-up roll grade has recently been launched. As next step increasing the field of applications is under progress.

Aug 17, 2017

By K. K. Kelley

Sodium-aluminum and potassium-aluminum silicates are among the more important rock-forming minerals of the earth's crust. They also appear as constituents of some metallurgical slags and of some refractory materials. Consequently, knowledge of their thermodynamic properties is interesting and valuable from several viewpoints. This paper reports experimental determinations of the low-temperature heat capacities and entropies at 298.16° K. of albite, jadeite, and nephelite it the sodium-aluminum silicate series and of adularia, ferriferous orthoclase, leucite and kaliophilite in the potassium-aluminum silicate series. Also high-temperature heat-content and entropy increments about 298.16° K. are reported for albite, jadeite, nephelite, and carnegieite in the sodium-aluminum silicate series. Except for a few high-temperature heat-content values for albite, all these data are available for the first time.

Jan 1, 1953

By C. O. Hawk

As an exploratory effort to produce useful products from coal by a new path, the Bureau has made a few experiments on the fast heating of finely ground coal particles by irradiation with a flash of high intensity light. The flash was produced by an electrical discharge at high voltage through a xenon-filled tube. The flashes lasted from 2 to 3 milliseconds. The reaction took place in small sample tubes, ½ inch-dimeter by 4 inches long, and with small amounts of coal (total amount charged 0.1 gram, probable effective amount not more than 20 milligrams). Average particle size of the coal, estimated on a numerical basis, was 20 microns. Temperatures reached were evidently quite high, because all products obtained in quantity were characteristic of high temperature pyrolysis. Apparently, conversion of the coal was extensive where isolated particles received the full benefit of a flash. It seems particularly significant that acetylene was present in appreciable amounts--comprising almost 3 percent of the total gaseous product in one case. This is good evidence of a short heating period to very high temperature (well above 1,000° C) followed by rapid quenching. Although the results are interesting, they do not suggest any immediate practical application.

Jan 1, 1963

By A Chandra, P Guj

Only a few complex real options can be valued using closed-form equations, such as the Black and Scholes formula, because these algorithms are restrictive and prevent the construction of practical project evaluation models. Although a binomial lattice method paired with the ærisk-neutral probabilityÆ provides an easier and flexible modelling of exploration and mining projects, it has limitations when projects are complex, long-lived and influenced by the interplay of various market and private uncertainties. In order to overcome these limitations, modern decision tree software using dynamic programming capability can be used for real option valuations. This is a powerful computational tool in which the impact of various sources of uncertainties can be differentiated, so that the optimal decision path can be explicitly displayed visually. There has been significant academic controversy surrounding whether different real option (RO) valuation methods would lead to different real option values (ROV). This paper, using a realistic copper mining example, demonstrates that as long as the same degree of subjectivity and consistency are used in different real option valuation methods, they yield the same result. This conclusion is valid irrespective of whether the cash flow volatility generated by various sources of uncertainties is handled in an aggregated or in an explicit and differentiated manner. This paper compares two choices for an investor either to æbuy now and developÆ a project or to enter into a ætwo-year option to purchaseÆ after the proponents have developed it. It also shows how significantly different net after-tax operating cash flows may be generated by these different choices on the same underlying asset represented by the project. This is due to the difference in the amount and timing of the relevant capital investments affecting the depreciation and amortisation charges and as a consequence, the income tax paid. CITATION:Guj, P and Chandra, A, 2012. Real option valuation of mineral exploration/mining projects using decision trees - Differentiating market risk from private risk, in Proceedings Project Evaluation 2012 , pp 177-188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By I. Abdullayev, M. Soberano Capistran, J. Garcia

The application of post-tensioning in segmental structures was introduced in the early 1900s and has been successfully applied in different types of structures including immersed tunnels, bridges, buildings, metro stations, and stadiums. There are, however, only five known circular concrete tunnel projects where the post-tensioning approach has been adopted. This paper discusses the application of post-tensioning to mitigate the high internal operating pressures in an effluent outfall tunnel project 7 miles, 11.3 km long, currently under construction for the Los Angeles County Sanitation Districts, LACSD. This project will be the first use of post- tensioned segmental concrete tunnel linings in North America.

Jun 23, 2024

By E Jak, P Hayes, J Chen

The paper provides an overview of the various analytical and microanalytical techniques currently in use to characterise the outcomes of pyrometallurgical processes, examining the advantages and limitations of these approaches. Specific focus with be given to quantitative microanalysis techniques including electron probe microanalysis and laser ablation, covering general principles, capabilities and limitations and recent development to address specific challenges associated with analysing molten slag, matte, and alloys, highlighting the necessity of embracing the application of these and other innovative analytical methodologies.

Jun 19, 2024

By R. Hogg, T. F. Dumm

"Procedures for particle size analysis on respirable dust from coal mines have been evaluated. Using respirable dusts dispersed in a laboratory dust chamber, size distributions measured using cascade impactors have been compared with the results of a variety of laboratory sizing methods performed on samples collected on filters placed side-by-side with the impactors. The laboratory techniques included centrifugal sedimentation, laser diffraction/scattering and automatic particle counting. The general agreement among the various methods was very good, with systematic differences which can be attributed to the different definitions of size used. Simple conversion factors have been obtained which can be used to transform the laboratory data to equivalent aerodynamic sizes.Similar comparisons have been made on samples collected in underground coal mines. Again, the results are in quite good agreement although small discrepancies were observed in· some cases. These have been attributed to some degree of agglomeration in the airborne dust, leading to slightly coarser apparent distributions in the impactor samples INTRODUCTIONA primary goal of mine ventilation is the control of airborne dust, especially in the ""respirable"" size range, typically defined as finer than about 5 to 10 µm. It follows that determination of the amount and characteristics of the respirable dust is an important factor in evaluating the performance of ventilation systems. Particle size information on airborne dust in mines is commonly obtained by in- situ measurements using cascade impactors. However, these tend to be inconvenient for routine data collection and the alternative approach of collecting samples in the mine, on filters for example, and returning them to the laboratory for detailed analysis is very attractive. Questions have often been raised, on the other hand, as to the appropriateness of this approach. How well · do such laboratory methods describe the distribution of aerodynamic diameter of the airborne dust particles in the mine environment? The purpose of the work described in this paper was to evaluate some laboratory sizing methods and to compare the results of such measurements with the size data obtained by the direct, in-situ method."

Jan 1, 1989

By David La Rosa, Matthew Craft, Lee Julian

Rules of thumb are ubiquitous in blasting. Typically presented as ratios, they assist with the initial assumptions of blast design and provide guidance for best practice. Examples include the blast hole diameter as a function of bench height, and stemming length as a function of hole diameter. The most common rules of thumb were developed in mid-20th century and it is important for a blaster to know if the rules of thumb are still reliable.

Feb 6, 2023

By Leonardo Soto, Fernando Villanueva

"Antofagasta Minerals S.A. (AMSA), for its Centinela District Project, is currently developing, at a first stage, a new 90 ktpd Concentrator Plant incorporating Esperanza Sur (ESP Sur) and Encuentro (ENC) ores. In order to dimension properly main equipment, specifically for grinding circuit, a final decision has been taken using geological and metallurgical (comminution) data from both body ores. Data was analyzed internally within AMSA and its consultants to get a final proposed circuit for further engineering studies. Specific Energy Consumption (SEC) parameter is one of the main key factors for proper dimensioning. To get an accurate value different tests have been made and modelled to ESP Sur and ENC ores. Also, operational data from Esperanza operation has been taken into account due to its similar ore characteristics to ESP Sur ore and incorporated as input data for design. Depending on data, quality and amount, it is possible to estimate accuracy for project investment and risk level, hence investment decision can be taken under good and reliable information."

Jan 1, 2014

By C. Eddine

"Can we use data to make communication effective? How does one successfully tackle the challenge of solving cultural differences and harmonizing the needs of diverse stakeholders while developing and maintaining a strong and reliable corporate image? Is it possible to achieve better engagement and minimizing risks with data? This paper aims to explore human rights and business procedures, the promotion of shared prosperity in a sustainable manner and the use of metrics to guide decision-making process. Among the topics examined are: • the significance of stakeholder engagement in community development projects; • the use of grievance mechanisms to give a voice to First Nations and communities / populations in vulnerable positions (including children and elders); • the benefits of configuring and implementing a feedback system in partnership with the communities. This research is a preliminary initiative and has limitations on the extent of the material used. The author acknowledges there is a vast amount of work and publications available on this subject, as well, as a variety of examples that have not been included. The intention is to keep developing this research to assess and expand how data can be used to minimize risks and improve engagement, in addition to inspire others to continue advancing this topic. Natural resources consumption is a reality that will not disappear in a foreseeable future. Several developments and operations are located in remote areas where communities in vulnerable situation and Indigenous Peoples live. Feedback systems are being ratified as a tool to help tackling the challenges of harmonizing cultural differences and fulfilling the needs of diverse stakeholders. Integrating social, environmental, and economic values plays an imperative purpose in preserving a productive and trustworthy relationship with stakeholders. Positioning social standards next to environmental and economic principles shows inclusiveness and firm intention of integration. We add value to a positive image of our industry by embracing responsibility for corporate actions and promoting their beneficial impact on the environment. The social context within communities, groups and organizations is dynamic and presents new challenges as connections evolve. There are wildly diverse expectations which one may need to address during exploration, construction and operating phases. Disagreements are an inevitable consequence of interactions due to the different needs and requirements of the parts involved. Nevertheless, balancing differences and solving conflicts can offer remarkable opportunities for improvement."

Jan 1, 2016

By Scott W. Hazen

COMPREHENSIVE summary is presented of results of several years of research at the Bureau of Mines Mining Research Center at Denver on adapting and applying techniques of statistical analysis in mine and mineral-deposit sampling and in computing grade and tonnage of ore for a mineral deposit. In addition to elementary statistical theory the material presented in the bulletin includes: (1) Certain special statistical techniques that have been found useful in mining applications; (2) problems, implications, and limitations that may be encountered in applying these techniques in mine sampling and evaluation; and (3) numerous examples to demonstrate application of the theory and techniques.

Jan 1, 1967

By G. H. Blackwell, N. I. Norrish

"At most operating mines, geostatistical are reserve estimation methods have been implemented by head office or consulting groups . With recent advances in small computer technology it is now possible for a remotely-located mine department to independently implement a geostatistical package.This paper describes the evolution of geostatistical routines to calculate the mineral inventory for porphyry type copper/ molybdenum or similar are bodies. The problems encountered in down sizing the geostatistical routines to run using limited minesite computing facilities are discussed. The high quality of the results, in spite of some compromises to geostatistical theory, is emphasized.The first stage entailed the development of a mineral inventory based on diamond drill data. The difficulties in fitting variogram models to two metals, copper and molybdenum, and the shortcomings of the mineral inventory due to the mixing of lesser quality exploration data with data from more recent diamond drilling are discussed.To improve the ore reserve estimates for short-term planning, a mineral inventory was produced using both the diamond drill and production blast hole drilling data. This inventory, when compared to actual grades, was found to be quite satisfactory for short-term planning. The inventory also provided a reliable data base for long range pit design and financial planning. By regularly updating the mineral inventory, many of the uncertainties of mining a low-grade orebody were minimizedIntroductionThe comparatively low grades of many Canadian mineral deposit s, the escalation of mine operating costs, and the volatility of metal prices in recent years, has required improvements to both short- and long-term mine planning.One of the prerequisites to improved planning systems is the need for accurate grade prediction. This paper describes the on-site implementation of geostatistical techniques for grade estimation of a porphyry I vein type copper/molybdenum ore body ."

Jan 1, 1987