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By David M. Abbott

This paper is a companion to, and amplification of, the ?History? section of the 2014 version of the SME Guide for Reporting Exploration Results, Mineral Resources, and Mineral Reserves (SME Guide). The need for the careful examination and evaluation of mineral deposits has long been recognized. In the book De Re Metallica, Georgius Agricola noted, ?Moreover, a prudent owner, before he buys shares, ought to go to the mine and carefully examine the nature of the vein, for it is very important that he should be on his guard lest fraudulent sellers of shares should deceive him? (1556, p.29). Agricola further stated, ?Now a miner, before he begins to mine the veins, must consider seven things, namely: the situation, the conditions, the water, the roads, the climate, the right of ownership and the neighbors? (1556, p. 30). The elements of Agricola?s seven things, much expanded, are incorporated into the 2014 SME Guide. As reflected in this quotation, veins were the primary concern of mining until 20th century technology permitted bulk mining techniques. The need for standardization of reserve descriptions arose along with the development of western mining in the United States and the concurrent development of mining engineering and mining geology as professions. By the turn of the century, debate about terminology of various classes of reserves was in full swing. Herbert Hoover noted in 1909 (p. 16-17), ?The old terms ?ore in sight? and ?profit in sight? have been of late years subject to much malediction on the part of engineers because these expressions have been so badly abused by the charlatans of mining in attempts to cover the flights of their imaginations. A large part of Volume I of the Institution of Mining and Metallurgy has been devoted to heaping infamy on these terms, yet not only have they preserved their places in professional nomenclature, but nothing has been found to supersede them. ?Some general term is required in daily practice to cover the available field of visible ore, and if the phrase ?ore in sight? be defined, it will be easier to teach the layman its proper use than to abolish it. In fact, substitutes are becoming as badly abused as the originals ever were. All convincing expressions will be misused by somebody.? Hoover (1909) noted that the common terms at the time were: ? Positive ore or ore developed: Ore exposed on four sides in blocks of a prescribed size. ? Ore blocked out: Ore exposed on three sides within a reasonable distance of each other. ? Probable ore or ore developing: Ore exposed on two sides, ? Possible ore or ore expectant: Ore in whole or in part below or beyond the range of vision. Hoover stated that these, and similar terms, overlapped and had the difficulty of failing to account properly for geologic variation in metal distribution beyond the exposed face. Certainly assuming extension of values along a vein is reasonable, but how far? Also, these definitions are for vein deposits, not all types of deposits are in veins. Hoover (1909, p. 19), therefore, defined the following terms. ? Proved ore: Ore where there is practically no risk in failure of continuity. ? Probable ore: Ore where there is some risk, yet warrantable justification for assumption of continuity. ? Prospective ore: Ore that cannot be included in the above classes, nor definitely known or stated in any terms of tonnage.

Feb 1, 2014

By Bernard L. Cohen

INTRODUCTION The most serious occupational radiation episode in U.S. history was the exposure of uranium miners to radon daughters in the 1945-1968 time period. Although the maximum permissible dose at that time was 12 WLM (working level months) per year, average exposures were several times that figure, and ten times higher exposures were not uncommon. Starting in the early 1960s, mounting epidemiological evidence appeared for an excess incidence of lung cancer among these miners; up to 1974, there was an excess of 134 cases (159 observed vs 25 expected) among the 4000 in the group under study (NAS-1980). When this excess became apparent, the Federal Government took jurisdiction, greatly tightened enforcement, and in 1969 lowered the maximum permissible exposure to 4 WLM per year. These standards were met largely by a great improvement in ventilation. As a result of these measures, average miner exposures were reduced 5-fold from 1965 to 1968 and by another factor of 3 by 1970. In 1978, the 4 WLM/year maximum permissible exposure was exceeded by only 37 of 7500 underground miners, for only 16 wars it exceeded by more than 25%, and for only 8 was it exceeded by 502 (AIF-1980). The average exposures to the various groups are listed in Table 1. We see that the average exposure for all miners was 1.03 WLM, and for those who worked essentially full time underground it was 1.45 WLM. For purpose of later discussion, it will be convenient to choose a single value for average exposures. In view of the fact that employment situations and job categories are bound to vary over a lifetime of work, we take this to be 1.3 WLM/year. The purpose of this paper is not to dwell on history, but rather to address the question of whether or not this present situation is satisfactory. This question was considered recently by a study group under the auspices of National Institue of Occupational Safety and Health (NIOSH-1980) and it answered the question in the negative, concluding that the maximum permissible exposure should be substantially reduced. However, their arguments were incomplete and were lacking in perspective. The principal thrust of this paper is to provide some of the material overlooked. RISK TO URANIUM MINERS FROM RADON EXPOSURE In order to quantify the risk to uranium miners under present working conditions, it is first necessary to estimate the risk of lung cancer per WLM of exposure. The most straightforward way of doing this is to use the data on the group of uranium miners under study. These are listed in Table 2 for 8 exposure ranges and for the total group (NAS-1980). If all data are given equal weight, the risk is seen to be 3.5 x 10-6 per year per WLM. Much can be said in favor of using this value for the risk as dose independent; it is within one standard deviation (SD) of the observations in 5 of the 8 dose categories (as expected from the definition of SD), and within 2 SD for all 8, and for the three cases differing from the mean by more than one SD, two are above and one is below. However, the uranium miner exposures in the present situation will be far below those covered in Table 2, so it is worth considering the possibility that the risk differs from this at low doses. From the last column of Table 2 we see that the experience from all exposures below 600 WLM indicates a risk higher than the mean for the entire group by more than two standard deviations (the value 600 WLM in this comparison was deliberately chosen to maximize this deviation; for exposures below 360 WLM and 840 WLM, the excess is only 1.0 and 1.6 standard deviations respectively). In view of this tendency for the risk to be higher at lower dose, we will take the risk to be 5.0 x 10-6 per year per WLM in what we will refer to as model A. This risk estimate is based entirely on exposures much [higher] than those that will be experienced by

Jan 1, 1981

By Dapeng Zhang, Brij Moudgil, Shibo Zheng, Chunhui Feng, Wenyi Song, Wending Xiao, Patrick Zhang

Separation of dolomite from phosphate is the most challenging problem in phosphate mineral processing. Over 50% of the future phosphate reserve in Florida contains too much dolomite to process using the current industry practice. The current phosphoric acid production practice requires less than 1% MgO in the phosphate concentrate as the feed material. The Florida Industrial and Phosphate (FIPR) Institute has collaborated with worldwide experts in the field to address this issue. As a result, the industry is now offered three feasible options. Option 1 offers three methods for reducing MgO content in the concentrate from the Crago process, including adding a dolomite depressant in the rougher flotation step, dolomite flotation of the cleaner concentrate, and scrubbing the cleaner concentrate in quartz sand. These methods could reduce MgO content in the final concentrate by 20–40%. Option 2 involves crushing and grinding of high-dolomite phosphate pebbles followed by dolomite flotation at slightly acidic pH using a new collector that does not require phosphoric acid as a phosphate depressant, achieving a final concentrate analyzing less than 0.9% MgO at about 87% P2O5 recovery. Option 3 is a gravity separation technique using an innovative separation jig, and its full potential remains to be demonstrated.

By Dragomir Gospodinov, Savka Dineva

A surprisingly large mining-induced seismic event occurred in the LKAB Kiirunavaara Mine (Sweden) on 18 May, 2020 at 03:11 (local time). The estimated moment magnitude was 4.2. The event caused extensive damage in a large section of the mine. The production in the area is not yet resumed, even by the beginning of 2022 (~20 months after the event). The Kiirunavaara Mine has one of the world’s largest underground seismic systems with approximately 253 geophones. The in-mine records of the event showed a very complex character with a several sub-events. The event was also well recorded by seismic stations out to over 9,000 km distance. Data from the underground and regional seismic systems were analysed to define and compare basic source parameters such as hypocenter location, seismic moment, as well as the seismic moment tensor. The data from the in-mine seismic system was used to study the development of the seismic process and to define elementary seismic sub-sources together with the official hypocenter location.

Apr 26, 2022

By K. L. Boyd

"Can the ever-increasing tonnages of ore and waste being mined today be accommodated simply by using bigger and better crushers? This paper reviews the latest primary crushing and large cone crusher designs. It highlights how—in addition to using the larger crushers now available—maximizing the utilization percentages in each of the four stages of the rock size reduction circuit will assist in meeting the larger production requirements of existing and new mining operations. Its goal is to help consultants and operators select the optimal equipment and custom-designed items in the material handling flowsheet from the mine to the mill, maximizing operating hours per year. INTRODUCTION Are larger crushers the answer to meeting the demands of existing or new mining projects for increased tonnage? Boyd (2002) predicted that larger crushers for primary and fine crushing would be beneficial and contribute to the further development of mineral processing. Larger crushers for primary and fine crushing applications are now available. The rock size reduction process from the mine to the selected milling process facility has not changed since man first broke a rock to get at the interesting mineralization within. The rock size reduction process circuit from the mine to the mill can be summarized in four stages: • Stage 1: Mining (rock breakage and fragmentation) • Stage 2: Pre-screening (scalping) • Stage 3: Primary crushing • Stage 4: Fine crushing (secondary, tertiary and quaternary) Plant throughput and ore delivery schedule will form the basis for flowsheet design and equipment selection. Once the project design criteria and the mine plan have been established, the circuit’s utilization percentage (percentage of hours when the circuit is being utilized) can be optimized for each of the four stages. The mining and process departments are the key stakeholders in the selection of the final comminution circuit, and both departments should be familiar with and contribute to the design of the circuit. This paper focuses on the four stages of a rock size reduction circuit from the mine to the mill, equipment selection, various ore and waste handling flowsheets, and improvements in crusher station design, all with the purpose of maximizing availability and plant utilization percentages. What is a large tonnage? From 1907 to 1914, the American Panama Canal excavated 300 million tonnes of material in 7 years (History of the Panama Canal, Wikipedia). Today’s large mining operations can move the same material in 10 months, using large crushers or multiple crushers for ore processing and large crushers and a mixture of truck haulage and conveyors for handling the large waste tonnages. Some examples include:"

Jan 1, 2017

By W. E. Lindquist

Roasting of refractory gold ores has the primary goal of oxidizing sulfides and organics to improve gold recoveries prior to leaching. Commercial installations currently utilize bubbling and circulating fluidized beds. The principle of flash roasting is aimed at a more cost effective method of whole ore roasting for large throughput applications. Results of pilot plant testing and scale up to commercial design will be discussed in further detail in this paper.

Jan 1, 1993

By L. W. Saperstein, MJ. Carlson

With the goal of improving the strength characteristics of pneumatically emplaced material used for localized subsidence control, the binding additives fly ash, bentonite, and portland cement were examined for their effect on the support capabilities of coal refuse. It was found that, within certain concentration ranges, all three offered some increase in the ultimate strength of the backfilling mixture. However, portland cement gave the greatest percentage increases. Selection of the appropriate backfilling mixture will allow for the most economical and efficient subsidence control when pneumatic stowing is employed.

Jan 1, 1990

By Andrew McGrath, Geraldine Lyons, Sarah Barcelona

In the dynamic and challenging modern industry landscape, understanding and unleashing the true role and contribution of technical teams is crucial to business success. The cyclical nature of industries has led to shifts in the technical professional’s place within the organization and the technical skills that are desired most. This paper reframes the pivotal role that technical professionals play within complex operating assets to maximize value and realize full potential. This investigation focuses on the Rio Tinto Kennecott Technical group’s cultural journey, which is underpinned by an investment in its people. The conflict between legacy industry beliefs and the necessity for cultural change emerges. This is illustrated by a deep dive into the evolving case study of Kennecott’s Bingham Canyon Open Pit Mine Technical team. Here, a multi-faceted approach to cultural change is helping to unlock the team’s contribution to the life extension of an aging asset. Guided by a vision and strategic roadmap, this approach is part way through a 5-year implementation period and is yielding encouraging business outcomes.

Feb 1, 2024

By R. S. Conti

The US Bureau of Mines (USBM) has developed an inflatable feed-tube seal (IFTS) for high-expansion foam generators. The IFTS is a lightweight, portable, rectangular inflatable bag that can be used by firefighters to rapidly seal large openings, such as those in underground mines, and to simultaneously provide a feed-tube for a high-expansion foam generator. Thus allows fire fighting foam to freely flow to the fire site and control or extinguish the fire. Studies indicated that a high-expansion foam plug will travel 183 m (600 ft) down an entry with a 4.5% rise in elevation, before leakage of foam from around the inflatable partition.

Jan 1, 1996

By Alizeibek Saleimen Nader

The intensive use of computers for mineral application at Serrana's phosphate mine in Jacupiranga, State of Sao Paulo, Brazil, began in the late seventies. The early hardware and software available are described in sufficient detail to allow comparisons between that solution and the new one, based on a personal computer and a new software package - PC MINE SYSTEM from GEMCOM SERVICES INC - that provides full color graphics capabilities plus mine design and planning tools. The process needed for adaptation to the new technology' and its impact on SERRANA S.A. DE MINERACAO are described. Finally, future enhancements to the System and mine control and planning are focused.

Jan 1, 1989

By J. M. Stewart

The incidence of heat stroke in the South African gold mining industry is today small (less than 1 in 10 6 shifts worked). Acclimatization and selection procedures have been developed and applied throughout the industry, underground working conditions have, and are being improved, and personnel are to-day made more aware of heat stress and its consequences than ever before. Although these actions have, over the years, brought about a steady reduction in the incidence of heat stroke (see Figure 1) the small incidence of heat stroke which persists indicates that heat stress is still a problem. This realization provides the stimulus for the work presented in this paper, which has as its primary objective the development of reliable heat stress limits for men working in South African gold mines. [ ] In keeping with recent trends3I4 the approach followed in this paper is based on the physical principles of heat transfer. Detailed studies of heat transfer from humans have been undertaken,5-l1 and certain of the results form an important aspect of this Paper -

Jan 1, 1980

By Wang Xuewen, Bao Qingbao, Xie Jiacheng, Yan Zewen

This study puts forward a virtual memory cutting method based on the prediction of AFC shape. The integrated key technologies include the generation of virtual teaching cutting curve, the height adjustment strategy of front and rear drum, cutting height adjustment strategy, the reciprocating cycle of cutting technology and so on. Through the two algorithms, SVM and ELM, the form of the next working cycle can be obtained by rolling prediction using the form information of AFC in the first several circulations. Based on the obtained dynamic fluctuation of the form in the vertical and horizontal working faces, the position and cutting information of the shearer during its operation can be controlled and predicted in advance, the memory cutting template can be adjusted and modified in time. Employing this method, the more stable, accurate and timely memory cutting of the shearer under the uneven coal seam could be realized.

Aug 16, 2021

By Andres Salazar, Carlos Delgado Robles, Richard K. Preece

Minera Escondida, located in the Antofagasta Region of northern Chile, is the world’s largest producer of copper as concentrate and SX-EW cathode. Projects to increase mill and flotation capacity began soon after start-up in 1990 to off-set decreasing copper grade. Subsequent projects had the objective to increase copper production through heap leach and SX-EW production and a second concentrator. The mine footprint concurrently expanded peripherally from the central high-grade enriched core of Escondida and then into the separate Escondida Norte deposit. Early in the mine life, metallurgical forecasting that was based on metallurgical composites of presumed ore types and historical plant production was adequate for operational planning, plant design, and project valuation. This approach became unreliable, however, as the increase in mine footprint was accompanied by an increased variability in key ore body characteristics such as hardness, copper-iron sulfide mineralogy, and sulfide liberation textures that were not reflected in the geological criteria used for ore type designation. The project study teams turned to small-scale physical and chemical tests to better characterize the spatial distribution of these key ore characteristics. Programs associated with capital growth projects were carried out through the mid-2000s to sample and construct a three-dimensional spatial model of hardness, copper sulfide mineralogy, and rougher flotation recovery from tests on 15-m drill core composites. Mathematical models were developed from the respective ore characteristic data to calculate throughput, flotation recovery, and concentrate copper grade. The spatial models were integrated with the concurrent mineral resource block model using standard geostatistical methods and the metallurgical process calculations were applied to the block estimates. The geometallurgical model, originally constructed on a project basis, is now managed by a dedicated team reporting to the manager of Geosciences & Resources Definition in the Escondida organization. The model has evolved with increasing complexity of the mine and processing plants and currently includes seven forecasting areas for three concentrators and four areas for two leach plants. Metallurgical forecasts of mill throughput, final flotation recovery, and concentrate copper grade still have the highest relevance to mine planning and optimization. Sample preparation, test procedures, and quality control methods are summarized for the ore characteristic tests important to these forecasts. Analytical results from recent annual sampling programs are presented for the hardness indices, rougher flotation recovery, and partial extraction copper analyses. Geostatistical analysis of the SAG mill hardness index is summarized as an example for the spatial estimation process. Mathematic models are presented for throughput (based on hardness indices), final flotation recovery (based on rougher recovery and plant calibration studies), and concentrate copper grade (based on sulfide mineralogy and empirical pyrite rejection studies).

Aug 31, 2023

By Subhash Bhagwat

The definition of high sulfur coal varies from plant to plant and is subject to changes over time as the environmental regulations change. In plants constructed after September 1978 hardly any domestic coal can currently be burned without the use of Flue Gas Desulfurization (FGD) because a 70 percent reduction in potential S02 emission is mandatory even when the potential emission is less than 0.6 lbs. S02/106 Btu heat input. On the other hand older power plants may in many cases be legally emitting up to 6 lbs. S02/106 Btu or more under some State Implementation Plans (SIP). The Clean Air Act requires, however, that in the long run all stationary sources of S02 pollution must abide by the ceiling of 1.2 lbs S02/10 Btu heat input.. Coals with a potential to exceed this limit must, therefore, be considered as high sulfur coals. Such a definition would be unrealistic because many SIP's aim at an emission level of 1.8 to 2.0 lbs. SO2/106 Btu for existing plants and a stricter limit does not appear to be enforceable in the next 5 to 10 years. As a result, coals with an emission potential of greater than 2.0 lbs of S02 per 10 Btu heat input are considered high sulfur coals for the purpose of this investigation. Based on this definition and the 1984 actual consumption of coals by U.S. electric utilities (table 1) only 7 out of the 24 coal producing states could be categorized as low sulfur states. The actual S02 pollution, however, depends on total tonnage of a type of coal as well as the sulfur content of the coal. Table 1 also indicates that only 6 states--Kentucky, Illinois, West Virginia, Ohio, Pennsylvania and Indiana-account for nearly 77 percent of S02 pollution potential in the United States. These 6 states have therefore been chosen for this investigation.

Jan 1, 1986

By Daniel Hodouin, Claude Bazin, Sami Makni

A method is proposed to perform on-line data adjustment and inference of unmeasured variables, using measured flowrates and on-stream assays in mineral processing plants. The algorithm minimizes a weighted sum of squared residuals of the measured variables and squared species imbalances around the flowsheet nodes. The method is based on a trade-off between the material transient accumulation, evaluated by the imbalances, and the data inaccuracies, evaluated by the residuals (i.e. the adjustments brought to the measured values). A recursive algorithm is developed for on-line implementation of the method. It is a real-time extension of the hierarchical method for balancing steady-state data for bilinear mass conservation constraints. An illustration for a simulated flotation circuit is provided.

Jan 1, 1995

By R. V. Ramani, S. Tan

A computer-oriented systems simulator (CMHS) has been developed for analysis of continuous materials handling systems. Special emphasis has been placed in the model on several features that are unique to these systems. These features include periodic pattern of material arrival from several sources, several types of material to he transferred, material dispatch processes, intermediate storage capacities, and multiple material destinations. Both the deterministic factors of the continuous material handling system, such as the physical decomposition of the system and the scheme and schedule of its operation, and the stochastic factors, such as variations of material arrival, material pattern on the conveyor, and availabilities of the system elements, are considered in the simulator. The application, of the model is demonstrated through a study of an underground conveyor belt network serving long- wall and continuous miner sections.

Jan 1, 1990

By S. W. Nicholson, L. G. Woodruff, K. J. Schulz, W. E. Cannon

The 1.1 Ga Midcontinent rift of North America has many similarities to the geology of the Voisey's Bay region in Labrador and the geology of the Noril'sk region in Siberia. These similarities include the hosting of large volumes of sulfur- undersaturated and trace-element-enriched basalt, having igneous centers characterized by crustal contamination, being characterized by metal depletions in some mafic units (an indication of prior sulfide segregation) and having known occurrences of Ni-Cu sulfide mineralization. These similarities along with new geophysical data and refined models for Ni-Cu sulfide deposits suggest that the Midcontinent rift probably contains undiscovered Cu-Ni [±] PGE sulfide deposits, some of which could be the size and grade of a Voisey's Bay or Noril'sk deposit. In particular, intrusions and related feeder systems that occur in northern Michigan and Wisconsin, as well as to the southwest along the rift margin, deserve serious examination.

Jan 1, 1999

By C. W. Nelson, A. G. Moody

This paper describes the design, equipment selection and onshore fabrication of the largest facilities module ever installed in a single lift in the Gulf of Mexico. Measuring 35.5 x 70.1 x 21.3 m (110 x 230 x 70 ft), the three operating level structure houses Frasch process sulfur mining equipment and weighed nearly 49 million N (5500 tons) during lift. An operating weight of over 74 million N (8300 st) combines with bridge reactions acting on the in-place module and results in a total operating vertical load on the supporting platform deck of about 107 million N (12,000 tons). A Vierendeel truss structural system was selected for framing the module to allow maximum equipment access and routing flexibility for complex, insulated large diameter process piping. Research and finite element analysis of crimp plate siding behavior in shear was carried out during selection of siding type for the module. An interactive design sequence was carried out that incorporated in-place operational criteria, onshore fabrication considerations, complex process equipment requirements, plus load-out, ocean transport and offshore lift analyses. Project schedule dictated that design, procurement and fabrication be fast-tracked with parallel activities accelerated to the maximum extent possible. Design and construction of this largest and most complex module was done concurrently with 52 other components of the project including jackets, decks, process and living quarters modules as well as two 122 x 22 m (400 x 72 ft) sulfur tankers. Total tonnage of steel structures for the project exceeded 90.7 kt (100,000 st). The 5 kt (5500 st) mining module proved the viability and costeffectiveness of larger modules than commonly used in Gulf of Mexico waters. This technical advance can be matched with economic opportunity for other large-scale offshore installations.

Jan 1, 1994

By H. E. Rojas, G. T. Adel

The primary objective of most comminution operations is liberation; however, mill performance is generally quantified in terms of particle size. Only recently has the use of image analysis equipment made it possible to quantify mill performance on the basis of liberation. In this investigation, a series of tests were carried out to study the effect of mill operating parameters on the liberation of sphalerite from a sphalerite/dolomite ore. The parameters studied included mill rotational speed, mill loading and ball size. The results of this work appear to indicate that sphalerite liberation is improved under conditions that promote impact breakage, while dolomite breakage is enhanced under attrition conditions.

Jan 1, 1992

By D. H. Stonehouse

There is no such thing as an industrial minerals industry. There are, however, many industries operating in the general field of industrial minerals. And although we use the phrase "industrial minerals industry" out of sheer convenience, the only common denominator among, say, the potash mining and processing industry, the sulphur-sulphuric acid industry and the granite industry is, in fact, that they each are exploiting an industrial mineral resource. May I quote the person whom I consider to be the reigning Mr. Industrial Minerals, Robert L. Bates, who in the 4th edition, 1975, of Industrial Minerals and Rocks states: "An industry is considered to belong to the industrial minerals field if its operations consist of extraction and processing, but not manufacturing. Thus the mining and beneficiation of feldspar is a mineral industry, but the manufacture of ceramic products is not. In the cement and lime industries, processing merges into manufacture, and the line is less distinct. It disappears altogether in a plant that extracts salt as artificial brines, and makes sodium and chlorine chemicals, all under the same roof."

Jan 1, 1981