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During recent years there has been a marked increase in the use of explosives in Queensland coal mines. Delay detonators have been introduced and their use has extended with the wider application of mechanised methods of mining.The need for careful study of the characteristics of delay detonators is stressed so that the advantages of simultaneous firing, from the points of view of safety and efficiency, may be obtained. With their use new potential hazards are introduced. These hazardsare considered and means whereby the overall safety may be improved are discussed.The increase in the number of misfires since the introduction of delay detonators is shown and the examination of misfired detonators is described. Lessons to be learned! from these misfires are noted and details are given of the essential requirements for safe and efficient blasting using delay detonators.INTRonUCTIONOne of the aims of mechanization in coal mines is to reduce the physical effort applied to the winning of coal. Explosives play an important part in achieving this and, following the introduction of power borers for the drilling of shot-holes in Queensland coal mines, much of the arduous work associated with coal getting has been eased. During recent years there has been a marked increase in the consumption of explosives, as shown in Table 1, and it must be the aim of all to use these explosives safely and efficiently. That there are dangers associated with the use Of explosives cannot be denied. The shotfiring operation is fully covered by legislation and, being under the control of one man, shQuld be capable of being carried out with a high degree of safety. The main source of accident appears to be the failure to take proper cover and this has resulted in...

Jan 1, 1958

By G. Stokreef, B. R. Davis, M. Kadiyski, Alvear Montenegro, H-P. Loock, V. Montenegro

An optical probe for burner monitoring in copper flash smelting, first developed at the University of Concepcion, is being industrially tested in a collaboration between Kingston Process Metallurgy, Aurubis AG, and Queen’s University. The sensor uses fibre-optics and optical emission spectroscopy to analyze the light emitted from combusting particles in the furnace reaction shaft. Information that can be extracted from the emission spectrum includes the temperature and brightness of the flame, as well as emission lines or bands from excited atomic and/or molecular species. Laboratory proof of concept testing of the sensor was first completed in a continuously fed drop tube reactor using O2/S stoichiometric ratios between 0.8–4.0. These O2/S stoichiometries capture the industrial operating condition, which is typically less than 1. The results from lab testing justified a plant trial of the optical probe, which was done in the Aurubis Hamburg flash furnace in September 2018. From this trial, approximately 31 hours of spectral data were collected and synchronized with furnace operating data. The results from both drop tower test work and the plant trial are discussed with implications for process monitoring in the commercial furnace. INTRODUCTION Flash furnace smelting is a continuous feed, batch tap, pyrometallurgical process. It is used to treat copper sulphide concentrates and small amounts of secondary materials, such as dust generated by the process. O2 enriched air and the concentrate blend are fed into the furnace reaction shaft through the concentrate burner. As the particles fall through the reaction shaft, they heat up and ignite, causing rapid, exothermic reactions that oxidize the iron sulphide, some copper sulphide and impurities in the feed. Reacted particles fall into the settler of the furnace, melt and separate into a matte and slag, while the SO2 enriched off-gas is carried out of the furnace for heat recovery and H2SO4 production. Operation of the furnace is achieved by adjusting a limited number of control variables. The main variables are the blast feed rate, blast oxygen enrichment, SiO2 flux feed rate and CH4 combustion rate (CH4 is used when the chemical energy of the concentrate is low) all measured relative to a set feed throughput. (Davenport & Partelpoeg, 1987; Davenport, King, Schlesinger & Biswas, 2002) The batch tapping nature of flash furnaces makes operation difficult because these control variables impact each other, and product quality can only be measured when matte and slag are tapped from the furnace. This means that operation of a furnace is based on feedback control from matte and slag assays. Because of the time-delay associated with understanding product quality, there is interest in using technology to monitor the combustion reactions that happen in the furnace reaction shaft.

Jan 1, 2019

By A. W. Breed

The bioleaching of arsenopyrite, the oxidation of arsenate and the precipitation of ferric arsenate are competing reactions, hence their rates depend on the relative concentrations of the respective species, and the activity of the bacterial culture. Bacterial arsenic resistance may be attributed to the Pst+Pit-mutation and an energy dependent efflux pump. Pst+Pit-mutations result in a reduced uptake of arsenate. This enables the bacteria to survive in solutions in which the arsenate concentration is significantly higher than the arsenite concentration. However, the excretion of arsenate requires energy. Therefore, in the absence of an energy source or during periods of reduced bacterial activity, the inhibitory effect of arsenate may manifest at concentrations to which the culture has been adapted. The chemical ferric leaching rate of pyrite and arsenopyrite decrease with a decrease in the solution redox and may be described using a modified Butler-Volmer equation. The bacterial ferrous-iron oxidation kinetics of L. ferrooxidans also depend on the redox potential, and can be described using a Michaelis-Mententype model modified to account for both temperature and pH. A model developed using the independently determined ferric leaching, and ferrous-iron oxidizing kinetics, has been shown to compare well with the experimental data for the continuous bioleaching of pyrite. Keywords: Leptospirillum ferrooxidans, arsenopyrite, bioleaching, sulphide minerals ferrous-iron oxidation kinetics, ferric leaching kinetics, redox potential

Jan 1, 2000

By S Durucan, A Korre

The application of simple methods of statistical analysis, coupled with geostatistical analysis and geographic information systems, can only summarise and give an outline of the spatial distribution of the parameters measured. Spatial analysis of the components or factors calculated, through principal component analysis or factor analysis, allows assessment of the geographical distribution of the dominant processes contributing to soil composition and/or contamination. Neither of these tools, however, distinguishes between the different sources of pollution. The application of canonical correlation to the data, driven by expert appraisal of the potential pollution sources, allows their quantitative and spatial assessment while GIS provides the environment in which to organise and present the results. The methodology is illustrated by its application to soil-contamination data from the Lavrio area in Greece, where silver-bearing orebodies have been mined for more than 25 centuries

Jun 21, 1905

By Gary Eck, Kevin Tallent

Over the past decades, the science of energetic materials has advanced dramatically in both the fields of military munitions, as well as industrial explosives. Out of necessity, test methods to measure the explosive performance properties of these materials were developed. As would be expected, these test methods have evolved and become more sophisticated with the recent advancements in electronics and computerized technologies.

Jan 1, 1998

By G. H. Lind

Research into the safe and economic extraction of underground coal pillars in the Witbank and Highveld coalfields of South Africa highlighted that future practices will have to consider pertinent risks associated with this least safe of all underground coal mining methods conducted in South Africa. To this end, a computer-based program called A-PEP (Analysis for Pillar Extraction Potential) was developed to assess three aspects of this mining practice, viz. risks associated with the physical attributes, operational risk attributes and economic attributes. This intelligent tool can thus be used when planning to conduct underground pillar extraction to ensure that all pertinent risk elements and legislative requirements are considered to conduct this mining method safely before a submission is made to the Department of Minerals and Energy. Keywords: operational risk management, mine planning, underground coal mining, pillar extraction.

Jan 1, 2003

Geostatistical methods have become well established in the last two decades for the evaluation of ore reserves in base metal, industrial minerals, coal and gold deposits of the Witwatersrand type. However, there has been considerable debate about the applicability of geostatistical techniques when applied to vein-type gold deposits with hydro or epithermal mineralisation. The main problems stem from a lack of spatial continuity and the highly erratic sample values that characterise these deposits. This paper reviews some of the current geostatistical techniques that are applied to the evaluation of gold prospects.

Jan 1, 1992

By J. S. Stachulak, K. A. Mackinnon

This paper deals with specifying and evaluating fans for mine ventilation projects. Topics such as fan and equipment design life, operating points, and operating conditions are discussed. Common operating problems, such as vibration, parallel operation, mechanical failure, erosion, corrosion, and deficient fan performance are covered. Apart from identifying the potential operating problems, likely causes and suggested remedies are given. Fan type, fan accessories, and likely system effects and fan testing are discussed. Suggestions on what should be covered when evaluating different fan options and proposals and suggestions on the verification of supplier claims and guarantees, including cost of operation, the evaluation of initial capital cost, estimate on maintenance costs, and likely replacement expenditure over the life of the fans. In addition, fan reliability, operational flexibility, suggested construction details and fan vendor past history and experience are reviewed.

Jan 1, 2004

By J. Darlington, A. K. SenGupta

Water-swellable layered silicates, namely, the smectite clays can remove suspended materials (called herein as debris) and metal ions from aqueous streams. The present study shows that the flocculating and metal extracting abilities of smectite clay-based flocculants can be enhanced when these clays are used in conjunction with a specific anionic polymer. Such performance enhancement is attributed to the following: i) the clay-dispersing ability of the polymeric additive, that would translate into an increase in the clay-surface area available for the attachment of the debris particles onto the clay particles; ii) the possibility of dispersant-to-coagulant transition of the polymer during the later instants of the treatment process, as a result of reduction in solvency of the wastewater for the polymer due to the release of cationic species from the clay-based flocculant solids; iii) metal-complexing ability and adsorption properties of the polymer.

Jan 1, 2002

By Deren Zhu

Based on the results of in-situ observations and physical model analysis, a computer simulation method, FEAEBP, has been developed to predict the behaviors of main roof breakage in longwall mining by considering it as a Kirchhoff plate on Winkler elastic foundation. This method in used to investigate the initiation, and development of the breaking process of main roof and its displacement field before and after its breakage. In this paper the simulation method is introduced, characteristics of the displacement field of the main roof is discussed and monitoring variation of the displacement field of the main roof in a Chinese longwall face is demonstrated.

Jan 1, 1989

During the drilling campaign conducted between October, 1942; and May, 1943, to prove the extent of the scheelite deposit worked by King Island Scheelite N.L. at Grassy, King Island, Tasmania, 35 holes were drilled and 606 samples recovered and assayed for their content. Of these, 238 came from outside the limits of the orebody and were for the most part barren, although a few contained some scheelite. The present statistical analysis is made only of the 368 samples taken from diamond-drill cores of the orebody itself.Drilling Pattern and Sampling MethodsFrom the purely statistical viewpoint, it is realised that methods employed in selecting sites for diamong.-drilling, and of collecting samples from drill cores, do not give a completely unbiassed set of data for analysis. Fig. 1 is a sketch plan showing the relativepositions of the drillholes, which were inclined at an angle of depression of 50 deg. The pattern does not conform to a properly randomized and' regularly-spaced grid, the positions of the later holes being determined by the results obtained from previous holes.Statistically, the bias is, therefore, favourable. The unequal spacing of the drill holes and the lack of uniformity in direction of the lines along which the holes were drilled are unsatisfactory from the mathematical viewpoint; but it is realised that these irregularitiesare difficult to avoid in determining by the most economical methods the extent of such an orebody, and are dictated by geological rather than mathematical necessity.Sampling, also, is lacking in complete uniformity. Each sample is approximately 10ft. in length. However, owing to the fact that 100% recovery of core is rarely achieved, and actual lengths of samples taken are ,primarily governed by the length of the drill runs,and secondarily by lithological changes, there is a considerable amount of variation in the sample length.AssayingWith the exception of 28 samples from three drill holes all samples dealt with in this paper were assayed in the Melbourne University Ore-Dressing Laboratory of the Commonwealth Scientific and Industrial Research Organisation. These assays were given to the nearest 0.05% WOg as it was considered that more accurate determination was not possible. This fact has been taken into consideration in the frequency analysis below. The 28 assays determined by the Tasmanian Mines Department were given to the nearest 0.01%.

Jan 1, 1950

By Eder Salazar

Como parte del desarrollo de sus operaciones de mina de cobre subterránea, la Sociedad Minera El Brocal S.A., desarrolló el método de minado tajeo por subniveles con pilares recorridas con el fin de incrementar su producción actual. En ese sentido, el presente texto señala la implementación de un método de minado conforme a las características geomecánicas del macizo rocoso del yacimiento.

Sep 12, 2011

The placer gold industry has experienced a roller-coaster history incorporating four major boom eras. The first, 'hand-methods' boom arose in the mid-19th Century from application of an old idea in new places around the globe. The subsequent hydraulic mining, bucket dredging, and 'hydraulic excavator-portable plant' booms each arose from application of new ideas in old places around the globe, ie in places where gold had been found during earlier booms. The new ideas that heralded the second, third and fourth booms were all significant advances in excavation technology. These enabled the industry to target the known deposits that were too deep, too wet, too small, or too low-grade for recovery by earlier boom methods. Relatively few new deposits or new deposit styles arose from the 'history book' exploration approach, so the number of known deposits to which each of the boom methods were applicable was limited. Consequently, the first three booms were each followed by significant periods of industry decline, and the fourth boom is currently waning inNew Zealand. Further decline is not inevitable and can be avoided by changing to a knowledge-based exploration approach similar to that adopted by the hard rock gold industry in the 1970s. Such an approach could easily herald the next placer gold boom.   Most of the relatively coarse, easily won alluvial gold in proximal and medial reaches of the active placer systems is gone. However, a substantial alluvial gold resource remains in the distal reaches of active systems, and in ancient placers formed onshore and on the continental shelf during previous sedimentary cycles. The resource in these deposits probably exceeds the total New Zealand placer production to date. Successful development of these placers requires application of robust geologic models for the formation and distribution of the placers through time, and advanced exploration technology that has not been used before in New Zealand. Nevertheless, the knowledge and technology required to explore and mine these deposits is available now. Many of these deposits contain a large proportion of problematic gold types that are difficult to recover with the commonly used gravity technology without sustaining significant losses. Despite advances in recovery technology in last few years, too much emphasis is placed on the incorrect assumption that gold size is the primary control on recovery efficiency. Other gold particle parameters, especially particle shape, exert a much greater control on whether gold will be saved or lost to the tails, and must be considered in the design of recovery technology and configuration of recovery circuits.

Jan 1, 2003

By Shuvranshu K. Rout, Anup K. Mandal, Biswajit Das, Manos De

"To adopt new technology advancement in Steel Plant, there is a requirement of shifting of operation process from Coke Wet Quenching (CWQ) to Coke Dry Quenching (CDQ). New CDQ chamber foundation with deep basement and underground conveyor tunnel are to be constructed in an operating plant where heavy foundations and structures are located in close proximity. Furthermore, the existing CWQ system will be in operation during new underground construction and erection. Challenges to deep excavation of tunnel and chamber foundation consist of non-uniform ground condition, prevent washing out of soil from bottom of existing foundations, stability of existing nearby structures, presence of large number of underground utilities, ensuring safe underground workplace to construction resources engaged in new construction work along with project schedule and budget constraints. A combination methods involving use of soil nailing, soil grouting, contiguous bored pile and micro pile had been adopted for protection of excavation sides as well as existing structures. Each side of excavation in different stretches were analysed during design as well as construction stages. The use of combination of all techniques in a single brown field project in context of the nature of site constraints and safety issues made this a unique project.INTRODUCTIONSteel Industry is one of the backbones of industrial growth of any developing country like India. Due to increasing land prices most of the steel plants in India are expanding within their existing plant facilities. In addition to that, there is demand of adoption of new technology for future expansion projects to set new benchmarks with global standards.The property owner had earlier installed a Coke Wet Quenching (CWQ) for their Coke Plant. Now, there is a requirement from process department to proceed with Coke Dry Quenching (CDQ). To facilitate the CDQ within the existing CWQ which will be in operation is the main challenge for the property owner. The second challenge is the limited space for underground construction and subsequent equipment erection within the stipulated time frame.From a geotechnical prospective, the project team had uncertainty and reservations in their mind about the construction methodology. Therefore, the role of three “C”: ‘Consultant’-‘Client’- ‘Contractor’ and their combining brainstorming is essential to freeze a working plan for achieving the goal. In this paper, only the excavation support systems for underground foundation structures have been highlighted in the context of solving geotechnical problems."

Jan 1, 2017

By D. Nag, J. Fernando

Hazelwood Power Mine is one of the largest open pit brown coal mines in Australia. The removal of overburden is the first step in coal winning operation. The primary aim of construction of overburden dump is to provide an effective stable working surface for stacker. The paper discusses site investigation techniques used to determine dump soil properties, stability analysis method using GALENA and GWEDGEM, results of stability analysis. The paper concludes with recommendation for a safe dumping strategy for level 2 stacker dumping.

Jan 1, 2003

By S. Hamilton

Borates are essential to life, and to many products that are essential to an acceptable standard of living. They occur naturally in seawater at an average concentration of five milligrams of boron per liter. Fresh water lakes, rivers, streams and ground water generally have concentrations of about one milligram boron per liter. Borates are also present in soil at concentrations ranging from 0.1 to three milligrams of boron per kilogram. Because most of that boron is locked into insoluble minerals, clay or organic matter, boron deficiency is more widespread than boron enrichment. Borates evaporate into the atmosphere from seawater, rain, snow and hot springs. In rain and snow, natural boron concentrations range from 0.002 and 0.1 milligrams boron per liter. All told, boron moves through the atmosphere at a rate of 5 Mt to 7 Mt/a (5.5 million to 7.7 million stpy).

Jan 1, 2005

By Zach Ahinga, Mike McRae, Dave Hopkins, Steve Klein

The San Vicente Pipeline project involves the construction of an 8-1/2 foot diameter water pipeline in an 11 mile long tunnel in San Diego, California. The tunnel will be excavated in extremely variable geologic conditions consisting of strong granitic and metamorphic rocks, weak sedimentary rocks, abrasive conglomerates, and mixed face conditions. This paper discusses the challenging geologic conditions and some of the key design evaluations for the project. Currently design work for the project has been completed and construction will be underway by mid-2005.

Jan 1, 2005

By R. Lombard

"Water is a very important component in the production process at underground coal mines. Current unfavourable economic conditions have forced the coal mining industry to identify and address every possible bottleneck preventing optimal production. An increase in water-related downtime was identified as one of the bottlenecks at Goedehoop Colliery’s Vlaklaagte Shaft. The purpose of this project was to identify the various causes that contributed to the high downtime (501 hours in 2013, which led to a potential profit loss of R12.9 million) and to suggest possible solutions.After a thorough investigation the main causes of water-related downtime were identified as low water pressure and low water flow caused by pipe leakages and bursts. The main root cause for the low water flow and pressure was identified as being the low pressure resistance (1600kPa) of the thin-walled galvanized steel pipes used in the underground inbye water reticulation system. The pipes were selected according to the previous 1000 kPa pressure requirement for the continuous miner. However, the pressure requirement changed to 1500 kPa, which resulted in the pipes being exposed to much higher pressures than designed for.The water reticulation system was reviewed and current and future underground pipe layout and water requirements were determined for the shaft. The time frame in which the water consumption would be the highest was determined to be between 1 January 2014 and 7 September2014. Machine and sprayer specifications were used to determine theater consumption at the shaft. Three different solutions were considered to solve the water-related downtime problem and to ensure the efficient supply of water to the newly open sections. Permanent underground concrete dams, semi-mobile dams, or new pipe columns with a higher pressure resistance of 3200 kPa were considered. A trade-off study (taking into consideration cost, time to completion and ease of implementation, maintenance requirements, safety, and flexibility) was completed to determine which of these solutions would be most viable.Paper written on project work carried out in partial fulfilment of B. Eng. (Mining Engineering)"

Jan 1, 2015

By Bruce I. Thomas

[THIS PAPER, tine of a series on placer ml n in iii Alaska, describes mining methods and gives unit costs at operations where hydraulic and mechanical excavation equipment is used with nonfloating washing plants. The mining methods described were developed during the last 30 years to copy with conditions peculiar to arctic and subarctic regions arid are now used by a large segment of the placer mining industry in Alaska. The operations described have been classified if m ii into three main categories: Those having sluices at a bedrock level, those having sluices above bedrock and those having mobile nonfloating washing plants (dryland dredges). Diesel-powered bulldozers and draglines convey or clevate gold-bearing gravel to the sluices, remove tailings, and strip waste gravel and other overburden. Diesel-powered centrifugal pumps supply water foe sluicing and hydraulic stripping. Detailed descriptions and unit cost arc presented for 14 operations to illustrate the numerous arrangements udder the first 2 categories.]

Jan 1, 1959

Study on the Reasonable Mineral Processing Technology of a Cu-Mo Ore

Sep 13, 2010