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Over the last two decades, the mining industry has spent considerable time and effort in installing sophisticated control systems (including expert systems) to regulate and improve the performance of AG/SAG mills. Yet the need for these systems is often overlooked – unmeasured and uncontrolled variation in the feed material. With AG/SAG mill technology replacing rod and ball mills as primary grinding equipment, the need for careful and thoughtful feed preparation has gone. To maximise mill throughput, operations need to better understand the ore characteristics affecting AG/SAG mill performance. Industrial operating data will be used to illustrate these ideas and concepts. It is often quite surprising which ore characteristics that are the most influential on mill throughput.

Jan 1, 2004

By K. A. Natarajan, Namita Deo

Strains of Bacillus polymyxa, preadapted and grown in the presence of corundum, were found to be capable of the efficient separation of hematite from alumina. Results of tests performed using binary hematite-corundum and ternary he- matite-quartz-corundum mixtures in the presence of cells and metabolic products separated from the adapted bacterial culture indicated that more than 99% of the hematite could be efficiently separated through selective flocculation after desliming. It was found that alumina-specific bioproteins and other nonproteinaceous compounds were secreted by bacterial cells after adaptation to the mineral. The utility of this bioprocessing is demonstrated in the removal of iron from bauxite ores through selective

Jan 1, 2000

By Norbert Patzelt, Johann Knecht, Wolfgang Baum

High pressure roll grinding (HPGR) is a mature but still expanding comminution technology. In the metals mining industry, HPGR is slowly gaining acceptance as a cost-efficient, high-throughput alternative for plant optimization. The increasing need to treat ores with progressively lower grades, complex mineralogies, refractory metal occurrence and variable rock types requires an energy-efficient comminution technology that reduces metallurgical problems inherent in conventional crushing and grinding, while stabilizing leach and flotation circuits and increasing metals extraction. This paper will summarize our latest HPGR pilot test results for gold and copper projects in the United States and South America and their confirmation through the first HPGR operation in copper mining. This paper will also stress the use of the high pressure grinding roll as a metallurgical tool. The application of HPGR for the treatment of heap leach SX-EW ores, semi-refractory gold ores, waste rock material and concentrator feeds will be illustrated.

Jan 1, 1998

By F. Daviess

A requirement for geological controls during orebody modeling results from the recognition of heterogeneous geological characteristics and/or abrupt variations in orebody geometries. While purely statistical methods are often sufficient for modeling uniform homogeneous deposits, and the only recourse for many that are extremely complex, geological interpretations can be extremely valuable as controls during the modeling process. The advent of relatively inexpensive, sophisticated graphical computer hardware and software has focused considerable attention on the three dimensional visualization capabilities now available to the mining industry. Orebody geometries can be easily imported into many systems as wireframe or solid models, rendered with shading and color, rotated in space, exploded into composite parts, zoomed into and otherwise displayed to awe any audience. The requirements for an initially meaningful, accurate, geological interpretation are sometimes lost when the focus is on an apparently complex, highly resolved end product. Details of the initial data and sensitivities of modeling assumptions are not always sufficiently scrutinized. Software capabilities have extended the geopoetic license into three dimensions. The new tools, while greatly facilitating model construction and rendering, have done little to expedite basic data preparation and analysis. This paper attempts to briefly summarize the purpose and method of the construction of geological controls. The examples selected are from wire­framing and block modeling; application software processes commonly used in the mining industry today.

Jan 1, 1992

By Abdellah Chlk, Driss Msatef

Sedimentary phosphate ores are known for their relatively high specific surface area and porosity, which have a positive influence on their reactivity when used as fertilizer in acidic soils or in the manufacture of wet phosphoric acid and phosphatic fertilizers. However, these physical properties could have a negative effect on the behavior of these ores if dried. This effect has been studied on several phosphate ores samples by: the determination of mineralogical and textural properties of these samples, the determination of vapor water sorption isotherms, at different temperatures, from which the sorption heat has been calculated, carrying out several drying tests using a laboratory fluidized bed reactor under constant conditions, which showed important differences in drying rates and residual moistures.

Jan 1, 1999

By B. Andersen, P. Somasundaran

An accurate knowledge of the interactions among mineral particles and between such particles and dissolved and precipitated species is important in developing efficient separation processes. In this investigation, interactions relevant to dispersion and selective reagent adsorption (the two main prerequisites for selective flocculation) within Florida phosphatic clay Waste were studied. Initial studies with artificial slimes, consisting of pure clay and phosphate minerals, showed dispersion of artificial slimes to be relatively easy. The problems that were encountered during selective flocculation of the artificial slimes were due to unselective polyacrylic acid adsorption on clay, which was caused by the presence of multivalent calcium ions on the exchangeable cation positions on the clay surfaces. This problem could be solved by exchanging calcium for sodium, which reduces the interaction between the polymer and the clay surface. This procedure, however, was not successful for mineral mixtures. Natural slimes were found to be much more difficult to disperse. This was attributed to the presence of cementing materials such as humic substances and Al and Fe (hydr)oxide precipitates. Selective removal of these cementing materials resulted in good dispersion and partial separation. A further increase in the separation of natural slimes is most likely determined by the presence of calcium on the clay surfaces, as was found for the artificial mixtures.

Jan 1, 1994

By Elnaz Saminfar, Jae Bateman, Eric Westergren, Mark Trim

This paper presents a case study of two major Australian infrastructure projects that used digital engineering to facilitate design delivery: WestConnex Project (Rozelle Interchange), and Sydney Metro West (Eastern Tunnelling Package). The paper presents project overviews and building information modeling (BIM) execution and focuses on modeling techniques, software utilization, data management strategies and how the digital models helped the design-build team mitigate impacts to schedule by identifying clashes between disciplines before the execution of work. Finally, it demonstrates the positive and transformative impact of digital engineering on the design and construction of large underground infrastructure projects and highlights its role in asset management throughout the project lifecycle.

Jun 23, 2024

By R. N. Chakravorty

It is well established that coal can react with oxygen in air at ambient temperature and as a result heat is produced. If the heat is not fully dissipated the temperature of the coal mass will increase, thereby enhancing the rate of oxidation with a greater production of heat. If this phenomena continues, the coal mass can ignite under favourable heat accumulation conditions. A number of mine fires are caused each year due to this phenomena, commonly known as spontaneous combustion. The early detection of spontaneous combustion is of prime importance to mining engineers since any fire which could be detected at an early stage may save the mine from considerable damage and subsequent loss of production. Obviously, there is no single general criteria by which one can assess whether the under- ground mining of a coal seam will result in liability to spontaneous combustion. This has made it imperative to develop systems for the early detection of heating and to follow its development. In recent years considerable advances have been made in the design and development of methods for the early detection of spontaneous combustion. The Mining Research Laboratories (CANMET) is presently investigating the problem of spontaneous combustion in coal mines with Kaiser Resources Ltd. at their hydraulic mine at Sparwood, B.C. on a co-operative basis, and some of the work was described earlier in the Canadian Institute of Mining & Metallurgy Bulletin (1,Z). This paper summarizes and updates the work done by CANMET on the detection of spontaneous combustion in coal mines.

Jan 1, 1980

By Robert D. Hansen, Richard R. Klimpel

INTRODUCTION A very important factor in froth flotation is the use of surface-active chemicals to form a froth in which minerals or coals are retained, thus allowing for valuable component enrichment. In coal flotation reagents (frothers) specifically designed to provide an efficient froth are employed. It is this group of chemicals that will be the primary emphasis of this paper. Despite the importance of frothers, surprisingly little systematic scientific work has been performed with the goal of quantifying frother mechanisms and the influence of particles on froth stability. Based on direct experimental observations in both batch laboratory and continuous large-scale flotation cells, the use of a frother significantly increases first, the possibility of a particle- bubble contact, and second, the efficiency of sticking after such a contact. Thus, a major role of a frother is to significantly increase the rate of flotation. This rate modification by a surface-active agent occurs through several observable mechanisms including the formation of a froth of relatively consistent character (bubble size and bubble density) under a variety of operational conditions, an increase in the ability to disperse air in the flotation cell, a reduction in the rate of coalescence of individual bubbles in the cell, and a decrease in the rate of bubble rise to the pulp surface. It will not be the intention of this paper to exhaustively list all frother accomplishments related to research, development and use in coal flotation. Rather, the authors will attempt, based on their experience, to present a technology overview of the role of frothers in the chemistry of flotation as successfully practiced at the industrial level. A very useful framework for flotation is the concept suggested by Klimpel (1984, 1984a) of viewing flotation as a system consisting of three major components: chemistry, equipment and operating variables. This is illustrated in Figure 1. A major point of this figure is that flotation is a highly interactive system with many technical and economic combinations of component settings available to operators to achieve a given goal. Sometimes simultaneously changing various component settings will reinforce a particular attribute. Also various component settings can cancel or counteract each other if changes are not chosen wisely. Thus, coal flotation must be viewed by the plant operator as a complex system with the economic/technical optimization of a given flotation process being directly related to the operator's knowledge of how his particular flotation system behaves as a function of the major control variables he has at his disposal. Typical important component settings in coal flotation are collector dosage, frother type and dosage, air flow rate, feed rate, particle size, pulp density, and the surface oxidation conditions of the coal. Because of the above complexities, it is sometimes assumed (especially in laboratory studies) that the choice of frother type and dosage is not as crucial as some of the other factors such as collector type and dosage (e.g., Leja, 1982). Detailed plant level testing of all of the factors of Figure 1 performed in recent years, Klimpel (1980, 1980a, 1982, 1984, 1984a), Hansen (19861, Klimpel, Hansen and Meyer (1982), simply do not support this assumption. The above testing has shown rather clearly that certain frother chemical structures consistently exhibit predictable performance characteristics in both mineral and coal flotation. In addition, significant changes in both rate and recovery can be expected. In the remaining sections of this paper, the following topics will be covered: requirements of chemicals capable of use as frothers, types of chemicals used commercially as frothers, some general performance characteristics of existing commercial frothers, and recent work in developing new frother chemical structures.

Jan 1, 1986

By S. S. Peng, Luo. Y.

In a shearer longwall mining operation, the longwall hits are responsible for breaking into and chipping the broken coal blocks away from the coal face. However, underground observations found that the bits being used were working under various degrees of wear. This wear can be reduced by using better-designed longwall bits and by properly selecting shearer operating parameters. A computer program was developed to simulate the performance of the longwall bits. The information required by the program are the shape of the bit head, the installation of the bits on the drum and the operation parameters. Through the simulations, the main factors affecting the bit-wearing process are identified. Suggestions are also made for improving the design of the longwall bits.

Jan 1, 1998

By Jeong-Heum Kim, Jan M. Mutmansky

The primary purpose of the research summarized in this paper was to experimentally investigate the performance of numerous mine ventilation network iterative solution procedures under controlled conditions to determine which procedures were most favorable in terms of number of iterations and total computational speed. The solution methods investigated included: (1) the Newton-Raphson method, (2) the Hardy Cross method, (3) the linear theory method, and (4) the second-order approximation method. The first three of these methods have been widely used while the fourth was formulated by the authors to investigate its potential for ventilation network computation. In addition to the four solution procedures, three methods for selecting the branches in the meshes and three methods for ordering the meshes for computational purposes were also studied during the investigation. As a result of these various options, a total of 36 combinations of solution methods, mesh selection procedures, and mesh ordering schemes were studied. To investigate the performance characteristics of these combinations, an identical set of 180 randomly chosen ventilation networks was used in sets of 30 networks at six different levels of complexity. Here, the level of complexity is defined as a function of the size (number of branches) and the density (number of nodes compared with the number of branches) of the network. To eliminate variations in the solution times due to differences arising from the fans, a single fan with a fixed characteristic was utilized in all the experiments. This paper will deal only with the results for the four iterative methods used to achieve solutions to the mine ventilation networks. The minimum-resistance spanning tree method for mesh selection and random mesh ordering was used throughout the analysis. The conclusions will be based upon a detailed accounting of the efficiency of each method using the total time to achieve a solution to each problem and averaged over the total problem set. However, the number of iterations and the time to complete each iteration will be studied in order to better understand the solution procedures.

Jan 1, 1991

By Eivind Grøv

"INTRODUCTION Tunneling and underground excavation is related to handling of uncertainties, risks associated with geological conditions are significant and ‘unexpected geological conditions’ often claimed. This fact was brought to the table long ago, and ITA (the International Tunnelling and Underground Space Association) published its 25 Recommendations on Contractual Sharing of Risks in 1988 (Ref. 1). This public-cation constitutes an important asset to the tunneling industry in terms of being a guideline for those working with contractual issues, even today almost 30 years after being published. A more recent document is the ITIG code of practice for risk management of tunnel works from 2015 (Ref. 9). Various countries or geographical regions have their own view and tradition on risk sharing and tunnel contracts. In Scandinavia unit rates contracts are most commonly used with bid-build model, it shares risk between owner and contractor, owner retains the risk for geological conditions while contractor carries risk for performance efficiency. Rock strengthening is determined assessing rock mass quality encountered at tunnel face. Grouting is applied to stem water. Actual quantities may differ from the contract’s BoQ but a flexible contract with remuneration is installed to enable adjustment of actual quantities. Variations of quantities involve a clause to adjust construction time. Unit price contracts deals with expected and foreseen still ‘unexpected geological conditions’, if the ‘unexpected’ element results in variations in quantities. Work activities have quantities and ‘standard capacities’ for regulation of construction time. Variations in quantities are expected in tunnelling and hardly deserve the term ‘unexpected’. If truly unforeseen geological features necessitate work not included in the BoQ, then the contract must be supplemented and can be said to be inappropriate. Fixed price contracts may not provide the intended predictable cost and is as such also inappropriate in the view of a risk sharing principle, once the geological baseline proves to be incorrect. ‘Adjustable fixed price’ contracts, combining unit rate and fixed price, may prove suitable."

Jan 1, 2016

By Joao B. Cardoso

This paper describes a two-stage reverse flotation method developed at the Mineral Resources Institute (MRII, University of Alabama, for Kerr-McGee Corporation (KMC), to separate the trona (Na2CO3 ? NaHCO3 ? 2H2O) from a saline deposit containing halite, borax, minor salts, and water insoluble materials. In the first stage, trona is depressed with Quebracho, and the insoluble gangue is floated with fatty acid. In the second stage, trona is floated with cresylic acid. The flotation concentrates contained better than 90% trona with insolubles ranging between 1 and 2%. Although the trona recoveries were low, optimization and middlings recycled in a continuous circuit could substantially increase the value.

Jan 1, 1989

ShouSteel Mining Ltd., a subsidiary of ShouSteel (Group) Co., was founded in 1959 and is located in QianAn City in Hebei Province, China. ShouSteel?s pelletizing plant uses iron ore as a raw material combined with limestone, dolostone, or olivine, with bentonite as a binder. After mixing the raw materials and forming them into small, spherical balls, ShouSteel then fires pellets in kilns for hardening. The company sells the finished pellets as raw materials for blast furnaces used to produce industrial metals such as iron. ShouSteel?s handling capacity is approximately 24.5 Mt/a (27 million stpy) of ore. The company?s production capacity is 3.2 Mt/a (3.5 million stpy) of oxide pellets and 560 Mt (650 million st) of sinters. Until recently, ShouSteel Mining had not replaced its electronic scales in its series of ingredient chambers. Because of the wear and tear on these older scales, the weighing system began to encounter regular problems. The company experienced a high failure rate from the integrator, an unstable signal, weak anti-interference ability and low accuracy. ShouSteel also found that spare parts required during repairs were consistently high in cost and that system calibration was becoming increasingly frequent.

Jan 1, 2012

By Yanchuan Li, Haifei Yao, Haiyan Wang

"Dust pollution is very serious in coal mining process, which is a great threat to the underground staff health and equipment and facilities safety. Coal seam water injection in mining process is an effective way to reduce coal mine dust concentration at the source. However, the effectiveness of water injection is limited in high-pressure and low-porosity coal seam. To improve the moisture content of coal seam, expand the wetting range and enhance the effect of dust reduction by water injection, the injectability and influencing factors of coal water injection are analyzed by numerical simulation method, and the sealing technology under high-pressure condition is studied. Then, according to the practical conditions of Tangkou coal mine, the parameters and process system of process system are designed, the effect of high-pressure water injection in coal seam was determined by testing water injection quantity, water increment and dust concentration. It is showed that the dust-removal rate of the high dust concentration operation such as falling coal and moving frame is 63.49% and 59.72%, the maximum dust-removal rate of multi-processes is 53%, which achieve a high level of application. The research results in this paper is of important theoretical and practical value to improve the water injection effect of high-pressure and low-porosity coal seam and improve the efficiency of dust removal in coal mining process.Introduction With the increasing of the depth and mechanization of coal mining, coal dust, the impact of ground pressure, ground temperature and other natural disasters continue to upgrade the harm degree (Wang 2011, Wu et al 2012), disaster incidents occur frequently, which seriouslythreaten the safe and efficient mining and the physical and mental health of underground staff. Coal seam water injection can effectively reduce the coal dust when coal crushing, prevent the impact of mine pressure, coal and gas outburst disasters, by increasing the thermal conductivity of coal, reduce coal temperature, and prevent spontaneous combustion of coal. In addition, coal seam water can soften the hard coal, so that speed up the recovery rate, improve coal production and efficiency (Wu et al 2008, Nie et al 2007). However, the coal seam in many mining area is with high-pressure and low-porosity feature, Coal joint cracks are not developed and relatively hard, water injection is difficult in these coal seams, then the desired disaster prevention effect cannot be achieved (Jin et al 2001, Zhao et al 2000). In this paper, the numerical simulation and field test methods are used to design the high-pressure and low-porosity coal seam water injection technology, so as to solve the difficult problem of coal dust control in high-pressure and low-porosity in deep well mining process."

Jan 1, 2017

By M. Ghiani, R. Ciccu

After a short review of the basic concepts underlying the application of selective flotation and electrostatic separation to the beneficiation of phosphate ores, the paper deals with the results obtained with these two technologies for a number of run-of-mine ores of different origin and distinct mineropetrographic features. Problems are discussed in the light of the minero-petrographic characteristics of the ores.

Jan 1, 1993

A number of factors have resulted in the widespread use of computer simulation as a day to day tool in the mineral processing industry, as is the case in most engineering disciplines. A number of simulation packages, both steady-state and dynamic are now available commercially. The developers of such software face an enormous challenge in maintaining and improving the packages due to the complexity inherent in such systems. This problem known as the software crisis faces all developers of complex software. Object-oriented (OOP) and design is a methodology which has been developed to try and minimise this problem. The use of the OOP paradigm in the devlopment of simulation software for mineral processing systems is explored in this paper and it is found that OOP techniques have major benefits for the design and development of such software.

Jan 1, 1992

By W. E. (Bill) Stanley

Introduction This is an exciting day. It isn't often that you can find the best minds in a particular business gathered together in one place. But that is what we have here. You are the best and the brightest people there are in the business of gold mining. What we discuss at this conference confirms the major issues facing us and sets out the issues governing how our mines and mining companies will be run in the next few years. In looking over the list of papers to be given, I have noticed something. It is something that I have noticed at almost every mining convention I have ever attended. Almost every paper at this conference concerns itself with the technical side of mining. Most of us in this roan are professionals; we are either engineers, geologists, accountants or representatives of some other profession. In getting where we are today, we have had to work hard to acquire the technical skills needed for our individual professions. We are all proud of our knowledge and work hard to claim the right to be considered an expert in a particular technical field or subject area.

Jan 1, 1987

By R. Aliberti, E. Comis, M. Wone

DC Water’s Clean Rivers (DCCR) program involves the construction of approximately 29 km (18 mi) of CSO tunnels in Potomac Group soils in the Washington DC area. Soils include an upper predominantly over-consolidated fine grained plastic material facies (P/A) and lower predominantly coarsegrained facies (PTX). As earth pressure balance (EPB) tunnel boring machines (TBMs) are mainly used in such soils, the correct approach to soil conditioning can make a considerable difference in TBM performance. Soil conditioning laboratory tests are often completed during the planning phase prior to TBM excavation to develop a baseline for soil conditioning, reduce risks, minimize costs, and improve performance. However, only a few basic tests are standardized to date, and conditioning regimes are fine-tuned during the mining phase. The paper illustrates the effort carried out to identify the correct soil conditioning regime for both PA and PTX facies to improve TBM overall performance and reduce ground movement during the excavation of the Northeast Boundary Tunnel (NEBT) in Washington DC.

Dec 1, 2022

By M. P. Meehan

The purpose of this paper is to present the key elements in a system; study of the electrical system for a timing and/or tilling operation. The ability of an electrical system to function in a reliable fashion at its proper levels is essential for an operation to be successful. A system study consists of a load study for determining the capability of the electrical network to provide power to the various loads and a short circuit study for determining the capability of the electrical protective equipment to properly protect against fault conditions. The sequence of events in a system study is data acquisition, determining the electrical parameters and analyzing the ability of the system to meet these requirements. If the system is small, herd calculations will be the manner in which the study will be conducted; if it is large then commuters will be used. A load study has as its objectives the determination of the capability and reliability of the source of power, transformers and conductors to satisfactorily deliver power to the loads at an acceptable voltage level. The Information required is a single line diagram showing the source, transformers, conductors and loads.

Jan 1, 1980