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By X. M. Prévost

The reassessment of coal reserves has become a matter of urgency and has come as a result of the present situation of the industry, in the context of globalized coal economies, as well as new mining legislation and the advantages and difficulties of domestic coal suppliers. The de Jager report concerning coal reserves, released twenty years ago, can no longer be used as an estimate for accurately forecasting South Africa’s future coal production. The new reserve and resource study will promote the diversification of energy sources and provide a clearer view of the future of coal mining in the country. With plans to increase South Africa’s coal export capacity to approximately 84 million tons by 2005, it is uncertain whether the country really has sufficient reserves to meet this expansion, as well as satisfy the projected increase in inland demand. The face of South Africa’s coal industry and by association, the economy of our coal-dependent country, are both set to change. This is mainly due to factors such as the demise of most of the large collieries over the last approximately twenty years, growing numbers of economic empowerment producers, the emergence of strong competition in the export market, the dawn of Clean Coal Technologies (CCTs) and the Kyoto Protocol The paper will attempt to dispel some of the current myths about coalfields and reserves and highlight potential areas of high quality coal reserves, available mainly to new entrants in the industry. Keywords: Central Basin, Clean coal technologies, Coal combustion, Coal exports, Coalfields, coalLink, Coal reserves, Coal resources, Coal processing, Colliery, Economic empowerment, Discards, Fluidized bed combustion, Low-ash coal, Metallurgical coal, Power generation, Pulverized fuel, Reserve blocks, Richards Bay Coal Terminal, Run-of-mine production, Saleable production, SAMREC Code, South Dunes Coal Terminal, Steam coal, Synthetic fuels.

Jan 1, 2003

Prof. Frank H. Probert, dean of the College of Mining of the University of California, visited the mining areas in the devastated regions as a member of the Bureau of Mines committee, which is studying the problems presented in the rehabilitation of mines there. He says that the absolute destruction of the coal mines in the Pas de Calais section makes it-necessary to use either the Westphalia or the Saar valley coal. The Saar mines, however, produce a poor quality of coking coal: therefore, it will not be possible to operate blast furnaces very efficiently unless provision is made for the introduction of better coal. He believes

Jan 6, 1919

By K. G. Markkola

Since 2005, Compafifa Contractual Minera Candelaria (CCMC) has defined various strategies which aim to optimize the usage of the available energy in each of the SAG grinding circuit modules (SABC-A configuration). For this purpose, the use of larger size balls along with operating with an optimum balls/load ratio has been implemented. Additionally, in the ball mills, the amount of balls in relation to the equipment's usable diameter has been optimized. In the pebble crushing circuit, the percentage of material passing 12 mm (112 in) product has been increased by 15% by: (1) modifying the crusher mantle profile, (2) implementing a strategy for maximizing the power in each crusher, (3) using continuous improvement tools (Lean - Six Sigma), (4) redesigning SAG mills discharge grates, and (5) changing discharge grates in order to control the crusher feed size distribution profile. All these activities have improved plant throughput by 1,000 t/d with no significant capital investment. As part of the energy consumption optimization study, we have considered determining the optimum operational rate of each SAG mill, in relation to the mill liner life and also the improving the control strategy in conventional grinding.

Jan 1, 2007

By Yan Yang

The Jinfeng gold mine is one of the three gold mines that Eldorado Gold has in China and it is the second largest gold mine in China. The mine is located in a relatively remote and mountainous area in the southwestern Guizhou province. The orebody is similar to the Carlin type deposit in Nevada. The mill throughput was designed to treat 3,600 tones per day. The ore comes from open pit mining and underground mining, and is fed to one-stage jaw crushing. The crushed ore is stockpiled, reclaimed and then fed to the SABC grinding circuit. After classification with hydrocylones, the ore is floated, and the resultant concentrate is oxidized biologically in a process known as BIOX®. The oxidized concentrate is then washed in a CCD circuit and finally leached with cyanide in a CIL circuit for gold extraction. Jinfeng produces about 180,000 oz of gold per year. This paper introduces operations and modifications of SABC circuit over the past three years, and then describes some technical characteristic of the SAG mill and other circuits in the processing plant. Major modifications and improvements on the SABC circuit are described in the paper, including: 1. Impacts of grinding ball and mill liner with respect to material selection, quality, hardness, manufacturing methods, and interactions between mill liner and grinding ball. 2. Effect of milling operation parameters on milling efficiency. 3. Impacts of SAG mill scats and modifications of grate size to improve mill throughput. 4. Design and construction of a pebble crushing system, and recycle the crushed scats to the SAG mill to improve mill throughput. With the above-mentioned modifications, 20% increase over the design in mill throughput has been realized over the past three years, and operating cost has been significantly reduced. However, some issues still remain, and thus process modifications and technical innovations are still needed.

Jan 1, 2012

By Chao Yang, Liguo Tian, Yan Yang

"The Jinfeng gold mine is one of the three gold mines that Eldorado Gold has in China and it is the second largest gold mine in China. The mine is located in a relatively remote and mountainous area in the southwestern Guizhou province. The orebody is similar to the Carlin type deposit in Nevada. The mill throughput was designed to treat 3,600 tones per day. The ore comes from open pit mining and underground mining, and is fed to one-stage jaw crushing. The crushed ore is stockpiled, reclaimed and then fed to the SABC grinding circuit. After classification with hydrocylones, the ore is floated, and the resultant concentrate is oxidized biologically in a process known as BIOX®. The oxidized concentrate is then washed in a CCD circuit and finally leached with cyanide in a CIL circuit for gold extraction. Jinfeng produces about 180,000 oz of gold per year.This paper introduces operations and modifications of SABC circuit over the past three years, and then describes some technical characteristic of the SAG mill and other circuits in the processing plant.Major modifications and improvements on the SABC circuit are described in the paper, including:1. Impacts of grinding ball and mill liner with respect to material selection, quality, hardness, manufacturing methods, and interactions between mill liner and grinding ball.2. Effect of milling operation parameters on milling efficiency.3. Impacts of SAG mill scats and modifications of grate size to improve mill throughput.4. Design and construction of a pebble crushing system, and recycle the crushed scats to the SAG mill to improve mill throughput.With the above-mentioned modifications, 20% increase over the design in mill throughput has been realized over the past three years, and operating cost has been significantly reduced. However, some issues still remain, and thus process modifications and technical innovations are still needed."

Jan 1, 2012

By J. Bartrum

Semi-autogenous, (SAG), milling operations can realize substantial Increases in mill throughput by removing and crushing critical size, slow grinding, material from the SAG mill. Full-scale plant testwork showed that modifying the Kidston SAG/ball circuit to a semi-autogenous-ball milling-crushing (SABC) circuit would increase plant throughput by 25 to 30%. The methods used to determine the value of the SABC circuit and the design of the circuit are discussed.

Jan 1, 1988

By A. Bhagwat, S. Tadolini

"Steel members of the ground support systems in underground mines are routinely exposed to corrosive environment that may range from acidic to alkaline. Corrosion of steel bolts leads to metal loss and thereby, reduction in strength and useful life. Protective coatings are commonly applied to the steel bolts to combat corrosion. However, coatings are expensive and often cumbersome in practical applications. Instead, Minova has developed an innovative technology based on sacrificial anodes. The anodes were designed from non-ferritic alloys that are inferior to steel on the Galvanic Series. This paper will present data from field testing to show significant benefit of the technology. Potential applications in current products will be discussed. INTRODUCTION Corrosion is a physical alteration of a steel material from electrochemical reaction with its environment that often results in reduction of the mechanical and physical properties of that material. Mine roof bolts, the subject of this investigation, are particularly susceptible to corrosion as they can be exposed in their working environment to ground water and air with high humidity. As other researchers have determined, corrosion increases markedly in sulfide ore bodies due to acid runoff. There are several types of corrosion that a rock bolt is likely to undergo when used for ground reinforcement in underground mines (Aziz et al., 2013). Of all the types of corrosion, pitting is particularly dangerous as it can remove capacity for the bolt to deform with subsequent strata movements. Sudden failure of a bolt is likely to occur when severe pitting corrosion is experienced. The type and nature of corrosion depend on the nature of the ground condition and bolt encapsulation. Generally, the type of corrosion and severity of the corrosion varies along the axis of bolt. Almost all of the mine roof bolts used in mines, with the exception of fiber reinforced polymers, are made from steel. The corrosion of iron is an electrochemical phenomenon with the overall equation:"

Jan 1, 2018

By J. E. Klein

Bench scale tests using a stack of ten whole SAES St909 pellets, 6 grams, to crack methane have been completed with pure methane feed. Test conditions ranged from 600 to 800°C at 101 kPa (760 ton) with a methane feed rate of ten sccm. Methane reformation tests, test where hydrogen was passed through a St909 bed after cracking methane, were performed to determine if and how much methane can be generated under "reformation" conditions. Phase structure determinations of St909, composed of a ZrMnFe alloy with aluminum used as a pellet binder, after methane cracking were complicated by the number of materials that can be formed by the elements in the St909 and the carbon from methane cracking. It was determined that the aluminum not only alloys with the Zr, Mn, and Fe in the St909 alloy, but also forms aluminum transition metal carbides in addition to ZrC as the carbon content and the temperature of the St909 increases. Some A14C3 was also found in some pellets. Passing hydrogen over St909 pellets after methane cracking formed methane at various rates in the temperature range of 600 to 800°C. Temperatures of 800°C gave the best methane cracking performance and efficiencies decreased rapidly with temperature.

Jan 1, 2002

By Riaan Van Wyk, Gys Landman

In today’s mining environment the use of radio communications in the form of two-way radios, cellular phones and even automated mining, form a vital part of the daily operations of a mining site. The radio transmissions that are used are a form of energy and as with all other types of energy it can have an influence on blasting equipment.

Jan 1, 2011

ALMOST all the hazards productive of accidents are present in churn drill operation-exposed electrical cables, open machinery, moving parts located overhead, exposure to weather, and movement of heavy machinery-all are part of the job. But, a check list of danger spots and full use of countermeasures will produce maximum safety here, as on any other operation.

Jan 8, 1953

By T. N. Singh, Vasudev Singh

Most of the surface mines in India have drilling and blasting practice as excavation method. All the mines have to keep the blast vibration level below a certain limit. But when mining operation is near some important civil structure, prediction and control of ground vibration becomes critical. Prediction of safe charge and finding the appropriate methodology is important for blasting near important civil structures.

Jan 1, 2006

By Mario Dobrilovic, Zvonimir Ester, Vinko Skrlec, Vjecislav Bohanek

The first public garage in the city of Dubrovnik has been built in highly urbanized area, on location Ilina Glavica. The excavation of the building pit has been done partly by construction machinery, i.e. by hydraulic hammer for excavations and partly by drilling and blasting. In the vicinity of the building pit there are houses, buildings and two schools. Drilling operations and blasting have been performed during the working hours while regular school classes have been held and activities in other buildings took place. The nearest structures are some 5 to 10 meters (16.4 to 32.8 ft) away from the building pit, which makes it even more difficult to perform blasting operations in the urban environment. For the purpose of determining safe and permissible oscillation velocity limits, i.e. the proportion of seismic effects of blasting, a trial blasting has been conducted. The permissible mass of explosive charge has been determined by original method respecting the requirements of existing standards (ISO 4866, DIN 4150, US BM 8507), which determine the permissible oscillation velocities in relation to their frequencies. According to measuring results of the oscillation velocity during the test blasting the design parameters of blasting field have been corrected and zones have been established within the excavation area considering the possible effect of blasting to the building pit environment. Further blasting operations have been performed in stages, in smaller blasting fields with deck charge within a blast hole while respecting the requirements of the transport possibilities for the blasted rock mass within the building pit and performance of control measurements of oscillation velocity for each blasting. Through application of all the protection measures, design solutions and systematic control of performance of activities the complete excavation by blasting has been completed without any damage on neighboring structures/buildings. This article presents these solutions and methods for reduction of seismic impact of blasting to the environment.

Jan 1, 2009

By Germán Toledo

The closure of TSF represents a critical milestone in the life cycle of mining operations, requiring the integration of technical, environmental, and social dimensions to ensure long-term safety and sustainability. The GISTM introduces the concept of “safe closure” as a demonstrable technical condition in which there are no ongoing material risks to people or the environment. This status must be validated by an independent technical reviewer and formally approved by the Accountable Executive. This article presents a risk-based methodology to support the achievement of safe closure, aligned with the principles and requirements of the GISTM. The proposed approach emphasizes the need to identify, assess, and manage closure and post-closure risks progressively throughout all phases of the TSF life cycle: from site selection and design, through construction and operation, to closure implementation and long-term monitoring. The methodology integrates key elements of effective risk management, including comprehensive knowledge bases, consideration of climate change, credible failure modes, continuous monitoring, stakeholder engagement, and governance. The ALARP principle is applied to demonstrate that residual risks have been reduced to tolerable levels. By incorporating closure planning from the earliest stages and adopting a risk-based view throughout the entire life cycle, this methodology aims to support mining organizations in achieving a verifiable and responsible closure of tailings facilities, in line with international best practices such as those of ANCOLD and ICOLD. The proposed framework offers a practical contribution to strengthening the credibility, effectiveness, and sustainability of tailings closure processes.

Feb 22, 2026

By Satid Therdkiattikul, Donald A. Dahlstrom

By oxidizing the pyrite matrix through biological leaching of precious metals ores or concentrates, better than 90% recovery of gold and silver is achieved. The paper develops three precipitation processes that eliminates arsenic and all other toxic elements in the resulting liquor after the biological reactors. In addition, the precipitates are highly crystalline and resist resolubilization. The latter must be tested for at least six months by EPA test procedures. The three systems are temperature (must be at least 120°C or higher) lime or limestone. A continuous pilot plant was employed for all three systems and complete recommendations are given to optimize Fe/As molar ratio, reaction kinetics (detention time) pH, temperature, wt % feed solids as well as resultant reagent consumption based upon continuous operation.

Jan 1, 1995

By Satid Therdkiattikul, Donald A. Dahlstrom

Many gold ores are known to be refractory so that conventional cyanide processing will result in serious losses of gold and silver values. A significant percentage of these refractory ores contain aresenopyrite and the gold and silver is usually encapsulated within this matrix as well as the pyrite matrix. Normally the values can be recovered as flotation concentrates because of the sulfide compounds with recoveries of over 90% and at very good grades. In order to free the gold and silver, the sulfide matrix must be destroyed. This can presently be achieved by (1) pressure­temperature leaching (2) roasting and (3) bacterial leaching. All of them have advantages and disadvantages as well as an obviously increased cost for the each processing method. However, the increased gold and silver recovery should and must more than offset this cost. It is believed that gold recovery should be well over 90% from the concentrate so that overall recovery from the ore should be in the 90-95% region. All three processes must consider pollution control of both sulfur and arsenic to prevent contamination of air, water or land through improper waste disposal. This paper will concern only bacterial leaching and its necessary control of effluents and solids. Sulfur does not appear to be a problem as the element is oxidized to sulfate and is precipitated with an acceptable solubility. Other important improvements that must be controlled are arsenic and iron which are present as significant values (1-12 g/1 of arsenic, 20-40 g/1 of iron). In addition much smaller values of base metals, aluminum and magnesium can be present as well as other elements depending on the ore and these must be low enough after treatment to meet EPA regulations.

Jan 1, 1993

By Ramie H. Thompson

1.1 BACKGROUND In many underground coal mining operations the use of electromagnetic field equipment, particularly communication systems, not only increases the overall efficiency of the mining operation but can be directly linked with mine safety considerations. The use of electromagnetic field producing equipment in underground coal mining operations can only be expected to grow. Several new communication systems have already been proposed. In addition, high-frequency producing equipments for many diverse uses in mining operations are under study. The use of these equipment in underground mining operations is hampered by the possibility of their electromagnetic fields interacting with the electric blasting cap operations commonly carried out in the mines. Such interactions can have at least two results bearing directly on mine safety: o premature initiation of the cap, either in its normal shot location or during hookup or transportation; o dudding of the cap so that normal firing operations do not cause irritation; thereby leaving unexploded high explosives after normal firing. Since the consequences of a premature initiation could, particularly in coal mines operations, result in catastrophe involving human life, the overall approach to prediction of possible hazard must be, as far as possible, of a "worst case" nature. The general problem of predicting possible RF hazards for any electroexplosive device (EED) is best treated by reference to Appendix A of

Jan 9, 1983

Permit quicker, safer clearance of hang-ups in the ore passes and chutes of underground mines. Approach Develop a device that can be operated from a safe distance to explosively propel a projectile into the hang-up. How It Works The Hang-Up Clearance Module, consisting of a stand, steel disk, explosive charge, and aiming device, is placed at a location convenient for line of sight aiming at the hang-up. This placement can be more than 100 feet from the target. Once aimed, the charge is remotely detonated, and the disk is converted by explosive force into a slug and propelled to the hang-up, bringing it down. The steel disk and an explosive charge are contained by a plastic casing. A small booster which is placed at the rear center of the explosive makes up the last component of the charge. Initiation is accomplished by standard means such as detonating cord or a number 8 blasting cap. When Initiated, a detonation wave travels through the explosive, inverting and consolidating the steel disk into a large slug. This slug is propelled at high velocity to the hang-up, delivering more than 5 million foot-pounds of energy on impact.

Jan 1, 1981

By Walter Ensinger

Special foundation works is one of the most innovative sectors in civil engineering and construction. Both engineering techniques and construction machinery are undergoing continu­ous further development. These developments are providing ways to meeting the world-wide requirement for special geotechnical works even faster, even better and more efficiently. Unfortunately, accident prevention organisations have had to realise that the figures on in­dustrial accidents in special foundation works are still above average in number. The Safety & Environmental Working Group of the EFFC thereupon started to carry out a survey on acci­dents occurring in this sector and used this information as a basis for the preparation of acci­dent statistics and an accident analysis. The objective of this undertaking is to determine key accident occurrences and their causes and to consequently determine measures for improved health and industrial safety.

Jan 1, 2002

Reduce injury to people or damage to equipment when a scheduled production blast is detonated. Approach The essential elements of an effective blast area security system were identified through case studies of five mining operations where the blast area guarding practices were considered to be superior to those generally found in the industry. These elements were used in making recommendations for improved blast area safeguarding practices. Background The blast area security system is a means by which the mine operator prevents injury to people or damage to equipment when blasting is performed. Analysis of blasting accidents showed that most blasting accidents occur during scheduled blasting and are due to inadequate blast-site security. Factors contributing to the system's breakdown are failure to clear the blast zone, inadequate guarding. and failure of personnel to follow instructions, retreat to a safe location, and/or take adequate cover. Mine personnel, visitors and even trespassers can inadvertently wander into a blasting zone unless proper procedures exist to ensure that all personnel are cleared from the blast zone and kept safely away until after blasting IS completed. Statistics show that the blaster is the miner most frequently injured In these accidents.

Jan 1, 1986

By Shamsher Prakash

Estimation of vertical load carrying capacity of a single vertical pile under earthquake loading is an important task of a design engineer. Lateral vibration of vertical pile is highly influenced by the magnitude of vertical load. Several load reversal, during earthquake loading introduce gap between pile soil interface which reduces its load carrying capacity and increases lateral motion. This paper presents a simple time domain numerical scheme to estimate the lateral pile response, considering the loss of contact of pile at pile soil interface, during impact and earthquake loading. The motion of the pile is limited in the vertical plane. Time domain has been discretised into small intervals. The non linearity of soil properties has been taken into account by discretised Winklers model with Wolfes frequency independent mass spring dash pot coefficient for geometric damping. Suitable software has been developed which keeps track of the load reversal point of each elements.

Jan 1, 1996