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This brief introduction tries to introduce delegates to this conference to the almost unbelievable attributes possessed by many microbes which might be relevant to geomicrobiology, and how most of these remain unexploited by us. It introduces some of the terminology which will be used and tries to suggest that there are rewarding times for those who set out to discover the natural biodiversity of bacteria in nature. Although we have exploited microbes, usually unwittingly, and suffered at their hands for millennia, it is only recently that we have begun to become aware of how they dominate our planet (most of the earthÆs biomass is bacterial) and are responsible consequently for most of what happens here. A few can cause us harm and occasionally kill us, but most bacteria are beneficial, impacting positively for example on how we grow our food and in cleaning up the pollution we create. They are simply indispensable to how we live. They have been responsible for many of the geochemical changes which have taken place on this planet and play major roles in the transformation of elements so essential to our existence (Newman and Banfield, 2002). No one should dismiss them as minor players in our game of life.

Jan 1, 2004

By J. R. Fisher

"Uranium may be leached to some extent in situ from the Blind River conglomerate uranium ores by using the products of bacterial activity from the bacterium Thio-bacillus ferrooxidans his paper describes some of the laboratory techniques used to investigate the characteristics of the bacteria, and to utilize their properties in uranium leaching. The application of some of the laboratory results underground at the Milliken mine of Rio Algom Mines Limited are de-scribed, along with the method of uranium recovery from the mine waters."

Jan 1, 1966

By R. A. MacGregor

The Stanreck mine of Stanreck Uranium Mines Limited in located on Quirks Lake in the Elliot lake - Blind River area of Northern Ontario. It is approximately 25 miles north of the north shore of Lake Huron, equidistant between the cities of Sudbury and Sault Ste. Marie. The property was developed ad brought into production at a rate of 3,000 tens of ore/day during the uranium boom of the mid 1950's. By 1960 mine waters were becoming quite acid through the activity of bacteria. Treatment of this water was begun for pollution control and a small amount of uranium which had been leached from the ore by these acid waters was recovered. Development of bacterial leaching with a view to increasing production by this method commenced in December 1962. Subsequently, it was succeesfull in producing 10,000 - 15,000 lbs. of U308/month. Since late 1964 uranium production has been obtained solely from bacterial leaching. A rare earth concentrate was also made for its yttrium content during 1966 and 1967. This paper describes the development, operation and methods used in the underground bacterial leaching process.

Jan 1, 1969

By Ralf Plinninger, Pafos Busch, Richard Gradnik

This paper presents the details of the Bad Bergzabern tunnel project. This tunnel is the main part of the B427 federal road bypass, intended to improve the regional traffic infrastructure and to reduce the traffic load in the historic city centre of the health resort Bad Bergzabern. Located in the south-western part of Germany, the project area is situated at the eastern margin of the so-called Palatinate Forest, a low mountain region of mainly triassic sediments with a complex and variable geological history. The German federal government, represented by the office of mobility of Rhineland- Palatinate, awarded the contract to BeMo Tunnelling, a specialized Tunnelling company with a long history of innovation and success in NATM tunnelling. The contract includes the construction of two separate tubes with a length of approximately 1,44 km (0.9 mi)—the road (main) tunnel with a cross section of 101 m2 (1,090 sq ft) and a parallel rescue tunnel with a cross section of ca. 23 m2 (250 sq ft.) Both are connected by six cross passages. Tunnels and cross passages are excavated according to the principles of the New Austrian Tunnelling Method (NATM). Due to BeMo Tunnelling’s technical expertise and capabilities, the project team was able to engineer a speed-up concept that saves money and time for the construction team and client. This paper presents the innovative approach BeMo Tunnelling made to optimize the execution of the tunnelling works and the challenges the project team is facing with regard to a complicated geological situation, countermeasures against an increasing effect of climate change and volatile prices for construction materials.

Jun 13, 2023

By S. K. Kawatra

It is common in coal-cleaning operations to produce a fine waste stream which contains a considerable amount of coal, but which is not economical to recover both because it is mixed with large amounts of difficult-to-remove clay slimes, and because the fines are often heavily oxidized. Conventional froth flotation machines cannot produce an acceptable product from such material in a single stage of flotation, and even flotation columns often have difficulty cleaning this type of feed. A new type of flotation column was designed specifically to deal with these problems, and was installed and tested in a coal-cleaning plant in Ohio. The feed coal contained 39.8% ash as fine clay, and 2.83% total sulfur, and was 80% passing 176 micrometers. The coal was a thickener product which had oxidized for some time, and was very difficult to float. However, using the new column it was possible to recover up to 85% of the calorific value in a product containing less than 11% ash, and up to 60% of the calorific value in a product of less that 8% ash. The bulk of the pyritic sulfur was rejected from the coal as well. Multistage flotation tests showed that the flotation column was able, in a single stage, to produce the best froth flotation product that it was possible to recover from this coal.

Jan 1, 1994

By Ernest R. Dickie

BRIEFLY, the ore body of the Bagdad Copper Corp., Bagdad, Ariz., is a monzonite porphyry carrying copper values fairly evenly distributed from the surface down through the primary zone. Tabular in shape, the ore body extends over several hundred acres. The oxidized zone averages about 60 ft thick and assays about 0.50 per cent copper. Under this is the chalcocite zone, or the zone of secondary enrichment, which averages about 100 ft in thickness and assays about 1.4 per cent copper. Under this zone lies the primary zone which extends in places to a known depth of about 150 ft and averages in grade about 0.60 per cent copper. Several years ago the block-caving method of extracting the ore from the chalcocite zone was installed. Then it was necessary to draw only about 250 to 300 tons per day, the capacity of the old milling plant. Early in 1943 the new 2500-ton concentrator was put into production. Drawing ore from the developed stopes in sufficient tonnage to furnish the mill at capacity proved unsuccessful in more ways than one. First, drawing the ore at an accelerated rate caused a large amount of dilution, there-by lowering the grade, and also caused funneling through to the surface. The surface material was detrimental to milling metallurgy and development of these stopes was costly per ton of ore extracted. The grade of ore decreased. making it impossible to maintain a mill head of over 0.9 per cent copper. The

Jan 1, 1947

By Edmund C. Bitzer

The unit costs of dry crushing, within the efficient reduction ranges of equipment now available, are considerably less than those for the reduction of the same material in the same size range by wet mills using grinding media. This is a commonly recognized fact which cannot be disputed; still we find considerable imbalance in costs between the crushing and grinding sections of many operating mills. In other words, there are many instances where more reduction could be accomplished in the lower cost area of dry crushing. In addition, equipment is now available which enlarges this area and makes it possible to consider much finer crushing than has been heretofore economically feasible. There has been a tendency for the past two decades to utilize wet rod-¬milling in the reduction step. This actually amounts to a fourth stage of crushing in a size range formerly served by roll crushers which have fallen from favor on account of high operating costs, Some investigations have indicated that there is not sufficient difference in the operating costs of rolls and rod-mills to give a clear cut advantage to either method, There has for some time been a need and an opportunity for a dry crushing process to improve costs in the range now served by these two systems.

Jan 1, 1965

By E. You

The concentrator at Kennecott Utah Copper currently has 4 lines with a configuration of one SAG mill feeding two ball mills. The slurry that reports to each ball mill will vary resulting in an unequal load of material. This configuration contains two separate sumps that receive material from a distribution box relying solely on natural slurry flow to feed each sump. The unequal split to each mill results in one mill receiving a greater amount of material. This will result in the equipment on one mill reaching limitations that may affect product quality and the operation of the equipment near maximum. The parallel mill in this condition will often have additional capacity that can be used but cannot be utilized due to the unequal split. The major consequences of this issue result in reduced throughputs and metal recovery. To resolve this condition an advanced control strategy was implemented to control the split in April of 2002 using equipment that was in place.

Jan 1, 2007

By Maryam Sadeghi, Jonathan Roy, Claude Bazin

"The operation of mineral processing equipments is intimately related to the mineral composition of the ore. However unit performances are usually characterized in terms of metal contents or recoveries as this data is easier to obtain than the mineral contents. This paper describes a method that combines the operations of material balancing and estimation of the mineral contents of the ore. The estimated mineral contents can be used for process analysis and diagnosis of operating problems.IntroductionThe ore that is feeding a concentrator is made of minerals that condition the energy requirements for the ore comminution and the performances of the subsequent separation circuit. Indeed a change in the mineral composition of the ore may lead to lower grinding mill throughput as well as lower recovery or grade of the economical products. Despite this relationship is recognized the mineral composition of the ore is seldom measured or estimated to provide regular information for the diagnosis of operating problems. Some methods such as the QEM-SCAN (Whiten, 2008; Lamberg and Vianna, 2006) are available to measure the concentration of the minerals in ore samples but the method is time demanding and plant operators usually base their evaluation of the plant performances on chemical assays of metals or elements since this data is easier to obtain from ore samples.Usually samples of the streams of mineral processing plants are collected on a daily basis to be assayed for strategic elements. The obtained concentrations are balanced to produce coherent data with the material conservation constraint and then used to characterize the day to day operation of the plant in terms of recovery of valuable metals and grades of the marketable concentrates. The behavior of contaminant elements can also be monitored from this data allowing the operators to explain for instance a lower zinc concentrate grade by a more important contamination of iron. However such diagnosis is only partial as the contaminant element can be transported by different minerals. Indeed the iron contamination of a zinc sulfide concentrate may be caused by an inadequate depression of pyrite or due to another iron carrying mineral. A possible way to answer the question is to determine the concentrations of the various minerals in the ore and produced sealable concentrates. Since measuring the mineral contents of the ore could be a demanding task one should consider to estimate this data from the daily chemical assays of the sample collected on the main streams of the circuit. Some authors have already investigated the problem. Whiten(2008) described a method to estimate the mineral contents of an ore sample. Lamberg and Vianna(2006) proposed a method to do a sequential mineral reconstruction followed by a material balance. Few of these methods account for the mass conservation of the reconstructed mineral contents."

Jan 1, 2016

By David Reddick

The mining industry is in the midst of dramatic change. Mining activities are moving from industrialized first world countries (Canada, Australia, and the United States) to the third world. This shift is occurring due to depleted reserves, tough environmental standards, and expensive labor in traditional mining countries. During a recent trip to South Africa, I was asked, owing to my educational background in economics and an international involvement in drilling and blasting, what changes could be anticipated in third world blasting practices as labor costs increase. It is from that beginning that this presentation has evolved.

Jan 1, 1997

One of the core tenets of Sustainable Development is transparency and information sharing, i.e., government and corporate reporting. Governments report on issues within their sphere of responsibility to the degree that their constituents demand that they do so. Firms undertake reporting for two reasons: they are required to do so by law, and doing so makes good business sense. In recent years, stakeholders have come to see themselves as having a right to information about government actions and business operations that have the potential to affect their lives, health, community and environment. As a result, disparate groups, including industry associations, non-profit groups, academics, and individual firms, attempted to lay out what governments and firms should report. There are many types of sustainability reporting. In this paper we focus on three of them that both governments and firms utilize. We discuss the benefits of each. We argue that while the goal of complete and perfect data is not achievable or feasible, sustainability reporting of all three types is necessary to ensure that sound public and private decisions are made.

Jan 1, 2007

By K. Thambi

The court in Baleni v Minister of Mineral Resources [2019] 2 SA 453 GP and [2020] 4 All SA 374 (GP), deliberated on the protection of rights of a community holding informal land tenure under Customary Law. The contention related to the necessary level of consent needed to acquire a mining right over such land. Moreover, whether consultations with such communities (Section 23, Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA) or consent (Section 2, Interim Protection of Informal Land Rights Act, No. 31 of 1996 (IPILRA)) was required to acquire such right. The case has a significant bearing on the granting of mining rights in South Africa, and the discretion of the Minister of Mineral Resources (the Minister) in this regard. However, the objectives of the MPRDA and IPILRA do not dovetail, therefore consultation and consent are not mutually exclusive (Tlale, 2020). This note argues that, despite the resounding victory of this case, the peripheral basis surrounding the decision and the various levels of engagement require serious deliberation. Equally, the degree of reliance on the IPILRA requires clarity to avoid aborting the fundamental objectives of the MPRDA. This paper provides considerations and recommendations that may reduce or eliminate the tensions between the statutory and socio-economic rights in the application of the two statutes.

Sep 1, 2022

By T. F. Deems

The nature, usage and comparatively rare occurrence of ball clay is described. The importance of these white firing plastic clays in ceramics, particularly in the production of industrial sanitary ware and tiles, is emphasized. The US deposits are briefly discussed. What is known about relevant deposits in Brazil, Argentina, Colombia and Venezuela (the four largest ceramic producers in South America) is also described. The ceramic plants have been sited near the centers of population rather than the plastic clay deposits. At present, extraction is probably concentrated on surface residual deposits and lenses which require minimum investment. Native plastic clays are used exclusively in the tile plants, but in sanitary ware, they are often used as extenders of imported ball clays.

Jan 1, 1997

By Omar. M. Arafat, Edgar Pérez, Kyle. M. Bartholomew, Robert. E. McIvor

The “circulating load” confounds understanding of ball milling circuits. Conflicting opinions exist as to its role. Should it be high, or low? Why does it even exist? It is commonly accepted in the plant as a given, the outcome of largely unknown factors. As such, it may often go unmeasured or even ignored. This paper describes the importance of the circulating load in wet ball milling circuits. It is characterized not only in terms of solids mass flow (or ratio of mass flows), but also by its other key physical characteristic, its size distribution. Its effect on grinding circuit performance is explained. The equipment application design steps to achieve a desired circulating load, in terms of both its mass flow and size distribution, are described. Finally, its pivotal role in grind control is specified. Our goal is for the reader to come away with a fresh understanding of the role of the circulating load in wet ball milling circuits, including how and why it should be measured and managed.

Feb 22, 2026

By O. M. Arafat, J. A. Finch

"The Functional Performance Equation calculated from a plant grinding survey defines two distinct ball mill circuit efficiencies and how they relate to total production rate through the target grind size. The survey data are also used to calculate a complete ball mill size distribution model, represented by the energy specific grinding rates, not just through the target grind size, but through all the size classes. Cyclone separation performance is represented by individual size recoveries to underflow. When these two unit operation performances are entered into the circuit modelling program (Streamline™), along with the circuit feed rate and size distribution, all the circuit survey size distributions and mass flows are perfectly regenerated by the program. The many issues associated with the historical Epstein (breakage-selection) models are eliminated. Once the circuit program is populated, pump and cyclone performance changes can be evaluated using a step-by-step procedure in order to maximize Classification System Efficiency. Mill water use and media sizing opportunities are also diagnosed in order to maximize Mill Grinding Efficiency at the size of interest. An example is provided. This circuit analysis and modelling system, and related training, is provided through a web-based application. INTRODUCTION Since its development (McIvor, 1988), the Functional Performance Equation for ball milling has facilitated new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this refreshing approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the Functional Performance “Mill Grinding Rate” at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining “selection rate” and “breakage size distribution” functions. The much simpler ball mill model presented here has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this extremely business-friendly ball mill model with optimization criteria from Functional Performance Analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/material provider, and circuit designer."

Jan 1, 2017

By O. M. Arafat, J. A. Finch

Since its development, the functional performance equation for ball milling (McIvor, 1988) has facilitated a new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the functional performance mill grinding rate at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining selection rate and breakage size distribution functions. The much simpler ball mill model has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this business-friendly ball mill model with optimization criteria from functional performance analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/ material provider and circuit designer.

Jan 11, 2017

By D. A. Longhurst

Improper size distribution of the grinding media in a multicompartment mill can be a source of many operation problems encountered. Inefficient use of the power expended for grinding, and an undesirable product size distribution are two frequent resultants. It is necessary to resize the grinding media in the leading mill compartment at time intervals related to the abrasive nature of the material being processed. In practice, this is done when time permits and with sketchy guidelines, if any. Maintenance of the grinding media size distribution can be scheduled, and would be, with a realistic method supplied to the user.

Jan 1, 1984

By T. P. Weldum, W. Conger

"The objective of the study conducted by the authors is to determine what media size(s) addition will maximize any given plant ball mill’s grinding efficiency (Fig. 1). The functional performance parameters “mill grinding rate through the size of interest,” and “cumulative mill grinding rates” from both plant and smallscale tests are applied to this task. A plant media sizing methodology, and industrial case studies, are provided.BackgroundA previous article (“Ball mill classification system optimization through functional performance modeling,” Nov. 17, McIvor et al., 2017, Mining Engineering) described circuit classification system efficiency (CSE), equal to the percentage of coarse (plus circuit P80 target size) material in the ball mill. It can be measured and then increased through pump and cyclone adjustments. By so transferring the application of ball mill power from fine (minus P80 product size) to coarse material, circuit efficiency is increased and overgrinding is decreased.The other factor that determines overall circuit efficiency is how well the power that is applied to the coarse material grinds it. This is affected by design and operating variables like the media sizing and mill percent solids. From circuit functional performance (McIvor et al., 1990):Circuit production rate of new fine material (t/h) = Power applied to coarse material (kW) x Mill grinding rate of coarse material (t/kWh) (1)The power applied to coarse material is the total mill power multiplied by the CSE. Therefore:Circuit production rate of new fine material (t/h) = Total mill power (kW) x CSE (%) x Mill grinding rate of coarse material (t/kWh) (2) Production rate, mill power and CSE can be measured during a plant circuit survey. The mill grinding rate of coarse material is then calculated. At the circuit target P80 size, this is the mill grinding rate (of coarse material) through the size of interest. The objective is to maximize this rate. The mill grinding efficiency can also be calculated by taking the ratio of the mill grinding rate over the material’s grindability as measured in the lab. Mill percent solids optimization has thusly been achieved (McIvor et al., 2000). For media sizing, maximizing the mill grinding rate on a given ore is equivalent to maximizing the mill grinding efficiency. Ores of different grindability will be part of the discussion."

Jan 11, 2018

By Alexander Gow

THE object of this paper is to discuss the fundamental principles of ball milling and to present some observations which have been made in laboratory and plant investigations. The discussion will be limited to wet grinding of ores in cylindrical mills, but doubtless many of the principles involved will be equally applicable in the other fields of fine grinding in which mills of the same type are used. In the concentrators of the United States there are about 650 ball, rod, or pebble mills, operating or ready to operate, and these have about 100,000 connected horsepower. For grinding in cement plants there is about three times this connected horsepower, and other industries have an unestimated amount, all used for the general type of grinding that is to be discussed here. It is true that these figures do not represent stupendous amounts of power, but when one considers that ball milling is often the "bottle neck" in a concentrator and that it often accounts for the largest single item in the cost sheet, the importance of a compre-hensive understanding of the principles of ball milling can be appreciated. Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses, or with the exclusive consideration of certain specific varia-bles, such as mill speed or circulating load, irrespective of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison, a new philosophy in the study of ball milling. Briefly, this "new philosophy" consists of using power as an index of the mill operation, and investigating grind-ing from the standpoint of set and induced variables, with emphasis on the latter.

Jan 1, 1934

This paper puts the view that, for one gold deposit in Victoria at least, the Australasian Code for the Reporting of Identified Mineral Resources is severely deficient. The author questions whether or not the Code constrains the proper dissemination of information relevant to resource valuation. The author offers a view about the estimation of inferred resources, and provides data believed pertinent to the proper valuation of Ballarat Goldfields Ltd Ballarat East Project.

Jan 1, 1990