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By J. R. Parga

In mineral processing, poor froth-flotation performance translates into both an enormous loss of revenue and an unnecessary waste of the ore reserve. In this context, Bacís Mining Company developed a versatile new, high-performance flotation-cell design that can be incorporated into various flotation circuits. The main feature of this circular cell is that it is comprised of two separate sections, namely, a flotation cell that uses wash water to minimize the entrainment of fine gangue particles into the froth product and an external bubble generator that produces small bubbles of relatively uniform size at a specified aeration-rate. The air/water mixture is blended with the pulp by gentle agitation, so as to enhance particle-bubble aggregate-stability. Comparative metallurgical performance with conventional flotation cells show that the power requirements and operating costs for precious metal flotation are three times lower, while the concentrate grade is 7% higher and the recoveries of precious metals are 5% higher.

Jan 1, 2009

By Raymond W. Henn

The 31th annual short course ?Grouting Fundamentals and Current Practice? was held at the Colorado School of Mines, in Golden, CO June 7-11, 2010. The field demonstration portion of the course was conducted June 10 at wlh Construction Co.?s yard in Denver, CO. The full-scale field demonstration presents many types of drilling and grouting equipment in operation as well as numerous grouting methods performed under various field conditions.

Jan 1, 2010

By C D. Rawlings

An assessment is made of the potential for thick seam underground mining of black coal in Australia. A brief summary is given of the geo-mechanical environment and previous mining history existing in a number of areas of particular interest from the point of view of thick seam mining. A classification of thick seam mining methods is presented with emphasis on the critical geo-mechanical parameters influencing the performance of such methods. A summary is made of perceived geo-mechanical research requirements related to thick seam mining in Australian coalfields.

Jan 1, 1980

By Donald R. McMahon

This paper presents a unique case history that documents the use of a braced secant pile wall to underpin a heavily loaded footing inside of a manufacturing plant. Construction of a pit for a new manufacturing process directly next to the footing necessitated the underpinning. The footing supports an overhead crane that needed to remain operational throughout construction of the pit and therefore, settlement of the footing could not be tolerated. The base of the footing was about 7.7 feet above the base of the 17-foot deep excavation. The footing bears on a silty clay deposit that grades from a stiff consistency beneath the footing to a soft/medium consistency near the base of the pit excavation. This paper describes the design and construction of the secant pile wall and bracing to control wall deformations, ground movements and settlement of the footing. The footing was monitored for settlement throughout construction of the pit and no measurable movement was observed.

Jan 1, 2006

Despite the recovery of approximately six million ounces of alluvial gold from the West Coast of the South Island, New Zealand during the last 140 years, a great deal of this having been obtained via sluice boxes and riffle tables, there has been little advance in riffle table technology during this period. In this paper contemporary riffle table design and current operational practices are examined. Studies of gold loss to undersize tailings are described. In addition recommendations derived from recent research carried out in North America are contrasted with gold saving strategies adopted by West Coast miners.

Jan 1, 1992

By Lonie W. M

The rapid development of the Australian steel industry over the past twenty years has greatly increased the demand for coking coal from the collieries owned by the Broken Hill Proprietary Co. Ltd. and Australian Iron & Steel Ltd. This in turn has called for an intensive and continuous programme of colliery expansion and new colliery development, along with the reorganization and modernization of existing collieries.This paper presents a general description of the factors involved and the techniques used in planning modern colliery development for the steel industry.PRELIMINARY GEOLOGICAL INVESTIGATIONSIn any colliery development, preliminary geological investigations require a detailed and practical knowledge of the geology and characteristics of the coal-field as a whole. In the early stages of the investigations, probably the most valuable information is obtained from outside the particular area under review, rather than within it, and unless the geology of the coal-field is understood, the projection of the known information into the unknown area cannot be carried out with certainty.Because development of the coal seams from the outcrops has been an apparently simple matter and not subject to the risks involved in deep mine development, the geology of the New South Wales. coal-fields has not received the attention that major mineral resources warrant.Only the most accessible regions of the coal measures have been generally prospected, while the potential areas remain...

Jan 1, 1957

Notwithstanding full concurrence with the dictum of a famous scientist that "definitions are the most accursed of all things on the face of the earth," in view of the considerable confusion which exists in jigging nomenclature, it is considered advisable to commence this paper with the following explanations of the terms which will be used throughout the text.Jig Bed. The whole layer of material lying on top of the jig screen.Ragging. The layer of denser material lying immediately above the jig screen, which is too coarse to pass through this screen and is confined horizontally by the cells of the top grid.Ore Column. The layer of ore pulp between the ragging and the top-water.Top Water. The water, carrying fine material in suspension, which flOiWS over the surface of the jig bed.Hutch Water. The water added to the jig below the screen. (Except for the water discharged with the hutch concentrate, the "hutch-water" eventually becomes "top-water.")Feed Water. The water in the ore pulp fed to the jig.(This water becomes part of the "top-water.")Pulsion. The period of the jigging cycle during which the water is moving upwards relative to the particles in the jig bed.

Jan 1, 1937

By S. O. Bada

Fine phosphate feed is considered to be slime and normally disposed of as a discard in settling ponds or dumped as landfill. The purpose of this research was to establish whether commercially acceptable qualities and yields could be obtained from this material using dry separation methods. The results obtained from the electrostatic separation of <105 µm phosphate ore are presented. An existing separator was upgraded in order to improve on product and flotation concentrate recovery, to test different mineral, and to reduce particle residence time between the charging chamber and the separating zone of the separator. The operating conditions were varied according to the charges imparted to the particles in the electric field, and according to other device parameters. Parameters such as splitter position, charge reversal, rotation speed, charging voltage and separating voltage. The <105 µm phosphate feed was concentrated under both triboelectrification and inductive charging. The use of inductive charging and charge reversal resulted in a significant increase in grade for <105 µm phosphate feed, with the P2O5 grade increasing from about 12 per cent to 20.50 per cent, and a recovery of 26.30 per cent under a single stage of separation. It was found that better separation was achieved at rotation speed of 6000 r/min, -8 kV charging voltage, and 25 kV separating voltage.

Jan 1, 2012

By Fathi Habashi

"Crushing and grinding of ores and their beneficiation by washing away gangue minerals has been practiced since ancient times. Primitive crushing was done by hand pounding the ore with a hard stone then by using metallic hammers. The mortar and pestle was mechanized using a lever and when the size of operations increased in the middle ages, the stamp mill was introduced. The grindstone played an important role in grinding of ores. Panning for gold and hand sorting of minerals were two old methods of separation, now gave way to modern techniques. Flotation started in the middle of the nineteenth century by using oils to collect the mineral particles and float them on the surface of the aqueous slurry. It was only in the 1920s when it was discovered that organic compounds were affective floating agents. Textbooks written by distinguished engineers such as Rittinger, Rickard, Pryor, Taggart, Richards, Gaudin, and others contributed to the recognition of this field as a new discipline to be taught in Universities. INTRODUCTIONThe ancient Egyptians knew already that it would be easier to melt an earth rich in gold particles than another which is poor. As a result all efforts were made to enrich the gold by washing away the light gangue minerals (Figure 1). Another ancient method for enriching gold particles from a river stream was by means of fleece, hence the Greek myth of the “golden fleece”. The present day Georgia was known in ancient times as Colchis and was a center for gold working. It was known to the ancient Greek as the land of Golden Fleece. The use of special cloth to catch gold particles was also described by Agricola in his 1555 book De Re Metallica (Figure 2)."

Jan 1, 2009

By G. M. Dowo

The widespread environmental damage caused by slimes dam construction requires rehabilitation as one of the key management strategies towards land restoration. From the time when Mhangura Copper Mine in Zimbabwe was shut down in 2000 due to viability problems, no follow-up studies were carried out on the slimes dams to assess their development with respect to ecosystem function and longterm recovery. The ecosystem function analysis (EFA) method was thus employed to achieve this end. EFA is a monitoring procedure that establishes how well an ecosystem functions as a biophysical system through the use of rapidly assessed field indicators. The field procedure makes use of simple visual indicators that are related to various soil surface processes. Conventional sampling methods are used to collect the vegetation data. The data was first analysed using landscape function analysis (LFA) software packages and then with various multivariate statistical techniques. In total 27 species were recorded from 14 families; 21 of them occurring in the acacia woodland and only 8 on the slimes dams. Hyparrhenia sp. was the dominant grass on Dam 5 and Imperata cylindrica dominated Dam 6. Acacia saligna was the most abundant tree species on the dams. The tree layer on the slimes dams was not as developed as the grass layer. The rehabilitated slimes dams converged with the natural woodland for the LFA indices of stability, nutrient cycling, and infiltration, which suggested a high level of functionality. The main factors affecting the sustainability of the rehabilitation are postulated to be fire, grazing, and tree harvesting. The study contributed to the importance of, and methods used for, assessing ecosystem function on rehabilitated slimes dams in Zimbabwe, which are often ignored as most efforts focus on the establishment of vegetation on the dams. Keywords ecosystem function analysis, EFA, mine tailings, rehabilitation, monitoring, Mhangura Copper Mine, ecosystem function.

Dec 1, 2013

By Greaves M. C, Amos M. D

A study was made of the instrumentation and technique of atomic absorption spectroscopy developed by Walsh of the Commonwealth Scientific and Industrial Research Organisation (C.S.I.R.O.), Australia.The method was evaluated for the determination of silver in lead sulphide concentrate. The precision of the procedure developed is equal to that of the uncorrected fire assay method and the accuracy is greater.Brief mention is made of the use of this technique for the determination of silver and other elements in ores and concentrator products.INTRODUCTIONThe fire assay method, although accepted on a world-wide basis as the umpire method for the determination of silver in ores and concentrates, is freely recognized as yielding results which are lower than actual due to unavoidable losses.King (1934) investigated the influence of the cupelshape, size and material on silver losses during cupellation. Using 100 mg silver prills he recorded silver losses ranging between l. and 10 per cent under extreme conditions and averaging approximately 2 percent under conditions which might be considered normal. Guerin (1957) made a detailed study, under carefully controlled conditions in a furnace similar to that described by Esdaile (1952), of the effect of temperature on silver losses during cupellation. He concluded that if cupellation were carried out at 840&#176;C., then the amount of lead retained by the silver prill was insignificant and that the silver losses were governed by the equation: Y = 0&#183;055 XO.74where X = the final weight of the silver priIl (mg)and Y = the silver lost (mg)

Jan 1, 1961

By Chikaosa Tanimoto

INTRODUCTION Bratislava is located at the intersection of important traffic routes, including motor-ways, roads, railways, air traffic, trading, and inland waterway with an important harbour. The construction of the D2 Motorway Bratislava, Lamacska cesta Stare grunty was the last missing section of D2 Motorway and its completion linked the Czech Republic through Bratislava to the Hungarian Republic. Traffic was obliged until its completion to use the Lamacska Road and Mlynska Dolina, which were the most heavily trafficked roads in the city. The section of D2 Motorway to be completed in 2006 was 3,300m in length, of which the SITINA Tunnel was approximately half the length. After putting into operation the transit traffic(motorway) and urban traffic was separated. Transit traffic by passing the town was eased. The junctions D2 with Lamacska Road (Harmincova) and Mlynska Dolina also allowed better use of the motorway for the urban traffic The tunnel construction was specified by the features with the highly weathered and thermally altered granitic rock formation with the overburden of Quaternary sediment of 2?4 m thick, very thin overburden, severely controlled deformation limit and environmental protection. The tunnel had to be excavated beneath and nearby the academic complex area and the zoo, where sensitive facilities exist and animals live in. The tunnel consisted of two tunnels (Tunnel A and B) with the length of 1,415 and 1,440 m, respectively. The overburden thickness was in the range from 10?30 m. The standard cross-section and the one with invert arch were 79.5?81.5 m2 and 92.1?93.3 m2. The excavation took 21 months from September 2003 to May 2005. The construction was based on the concept of NATM. The SITINA Tunnel was the third application of NATM in Slovakia, following the BRANKISKO Tunnel (commenced in July 2003) as the first and the HORELICA Tunnel (in October 2004) as the second NATM practice. To protect the surrounding structures and citizens from tunneling operations, seismic monitoring was performed in association with blasting. The allowable limit of blasting vibration was fixed to be under the particle velocity of 15 mm/sec. The tunnel excavation cleared this limit as expected before construction. In driving through the difficult geological situation the excavation work hit 49 faults, and some of them occasionally caused serious face instability. In principle, the rock formation has been affected by the high hydrothermal effect and the resultant clay filing along faults and joints. The auxiliary reinforcement with the 4?8 m long pipe roofing was needed to protect the vicinity of mining face area. This operation extraordinarily required additional works and time which had not been expected before construction.

By Erin Legault Seguin, Mike Rylatt, Curtis Mohns

"With energy costs increasing and ore grades diminishing, the role of pre-concentration in hard rock mining operations has been gaining greater interest. To maximize energy conservation, the pre-concentration process should be conducted at as coarse a crush size as possible while minimizing losses of pay metals. Dense medium separation (DMS) is a robust process that can be conducted at particle sizes as coarse as 300 mm and as fine as 500 µm with high separation efficiency, depending on liberation characteristics of the value minerals. The DMS process involves three steps: feed preparation, dense medium separation, and ferrous-based media recovery. This paper discusses each of these processing steps, but focus will be given to the dense medium separation stage. Various types of DMS equipment are reviewed. Pilot plant campaign case studies conducted at the SGS Lakefield site are presented, which have included a variety of mineral systems such as spodumene, sulphide-bearing gold ores, and complex sulphide ores. These case studies demonstrate that for amenable ores, mass rejection of 20-60% is possible while maintaining recoveries of greater than 90% in most cases.IntroductionPre-concentration is a process of rejecting mass of gangue while ensuring recovery of valuable minerals prior to more intensive, downstream processing. Pre-concentration has been practiced in industry for many years, and is gaining greater interest as the industry copes with processing lower grade, more difficult ores, typically requiring finer grind sizes and higher energy costs."

Jan 1, 2016

Recovery of Fine Gold Particles from Philippine Gold Deposits by Enhanced Gravity Concentration and Flotation The objective of the study is to determine the applicability of enhanced gravity concentration (EGC) and flotation for gold recovery. While gravity concentration methods have long been applied to gold ores, especially to free-milling types that requires minimal beneficiation, flotation for gold recovery has not yet taken hold as a major operation in the Philippine setting. In this study, the application of EGC and flotation for gold is applied and compared to the existing methods for gold recovery. Two samples, with assays of 7.315 and 5.333 g Au/MT (samples 1 and 2, respectively) are used for this study. These samples are subjected to mineralogical studies and is found to have a gold-particle size ranging 10 to 200 microns. To verify the separation size, the mesh-of-grind (MOG) is used as the primary parameter for experimentation. Initially, the samples are stage-crushed, ground, and subjected to EGC using a Falcon SB40 Concentrator. Based on the results, the two samples showed that recovery increases with a finer MOG. The ratio of concentration (K) decreases with a finer MOG. This shows that there should be sufficient liberation of the gold values for EGC to be effective. The effect of the enhancement is to pronounce the difference in specific gravity of the minerals, promoting better separation. This is validated by the high recovery values of 86.97 per cent and 98.73&nbsp;per cent exhibited respectively for samples 1 and 2 (at 54 microns). For the flotation runs, sample 2 with an average particle size of 80 per cent passing 74 microns is examined using thiocarbamate-based collectors for roughing and subsequently exhibited a recovery of 96.32 per cent. At this point, the concentration ratio (K) is noted as an important efficiency indicator for flotation process since it yielded a very low-mass and high-metal content concentrate.

Sep 13, 2010

By H. T. Kennedy, S. M. Avasthi

An equation developed for gaseous hydrocarbon mixtures predicts molal volumes with an average absolute deviation of 0.73 percent when applied to 264 natural gas and condensate systems including 2,043 PVT points. Another equation developed for liquid hydrocarbon mixtures predicts molal volumes with an average absolute deviation of 1.12 percent when applied to 346 crude oil systems including 1,759 PVT points. Both equations require composition of the mixture to be expressed as mole fraction of methane through heptanes-plus, hydrogen sulfide, nitrogen and carbon dioxide, together with the characteristics of the heptanes-plus fraction in addition to the temperature and pressure. The equations cover wide ranges of the variables involved, and their accuracy is considerably better than that of other available methods. The equations were differentiated to allow calculation of the coefficients of isothermal compressibility and isobaric thermal expansion. (In this paper the coefficient of isothermal com-pressibility and the coefficient of isobaric thermal expansion will be expressed as compressibility and thermal expansion coefficient, respectively.) Equations to calculate these quantities are presented. INTRODUCTION Calculations of reservoir performance for petroleum reservoirs require accurate knowledge of the volumetric behavior of hydrocarbon mixtures, both liquid and gaseous. Compressibilities are required in transient fluid flow problems, and thermal expansion coefficients are important in thermal methods of production. An accurate laboratory investigation of the PVT behavior of each reservoir fluid encountered would be costly and time consuming. For this reason various correlations for predicting fluid properties have been developed and recorded in recent literature. Correlations have been presented in the form of graphs, tables and equations. Since an increasing number of studies are being conducted with the aid of electronic computers, recent efforts have been directed toward development of correla-tions suitable for computer programming. Application of computers permits the use of more complex correlations which otherwise are not feasible. Moreover, methods for predicting reservoir performance, particularly those based on the compositional material balance, depend upon the capability of accurately expressing the molal volumes and other fluid properties as functions of pressure, temperature and composition. The coefficient of isothermal compressibility c is defined by

Jan 1, 1969

By Steve Kral

The mining industry has had three difficult years. Commodity prices have remained low and investor confidence in the industry has been shaken. And even though the Asian economy appears to be improving, it will be some time before this improvement will translate into better commodity price conditions for mining. In addition, increased environmental and social restrictions that have been placed on the industry in developed and developing countries have made mining a more difficult proposition. And, if that is not enough, the global mining industry has found itself in fierce competition with Internet businesses for investor capital. Despite that gloomy picture, more than 10,500 mining industry professionals from about 70 countries gathered in Toronto, Ontario March 5-10, 2000 for the Mining Millennium 2000 conference. This meeting was a joint effort between the Canadian Institute of Mining, Metallurgy and Petroleum(CIM) and the Prospectors and Developers Association of Canada (PDAC).The joint meeting also featured two trade exhibitions and more than 150speakers. PDAC’s trade show attracted about 400 exhibitors and an additional 200 in the concurrent Investors’ Exchange. CIM’s exhibition attracted about 600 equipment and service companies.

Jan 1, 2000

By Halvorsen N

For mining medium-hard materials on the surface, "Continuous Surface Miners" have been employed for some years. The latest generation surface miner extends the performance of this type of machine to the point where the same cost efficiencies can now be achieved in medium-hard materials as has been achieved in softer materials by machines such as the bucket wheel excavator. The paper explains briefly the technology of the Krupp Surface Miner (recently released to the market) and develops the costs of ownership and typical operating costs. Comparisons are made between a shoveLtruck system and Krupp Surface Miner (KSM) systems based on both truck and conveyor transport systems. Further benefits of mining with the KSM, such as environmental, selective mining and improved product reovery are discussed briefly. The equipment is now available to mine semi-hard materials (with compressive strengths up to 60MPa) on a continuous basis and reap the benefits which continuous systems can deliver. All new and existing open cut mines should review their costs with regard to this technology.

Jan 1, 1990

By Phillip M. Dight

A number of impending and actual pit wall failures have been observed and documented which have been interpreted to initiate on newly generated structural features. This infers failure through intact rock. Failure mechanisms have been postulated resulting from circumferential stress, extensional strain and brittle flexure. These will be discussed in the context of the failures and the associated monitoring. The implications of failure initiating on ?unknown? features has a significant impact for deep open pit mines where designs are based on the expected structural regime. Being able to anticipate such failures is important for design. Equally important is management of such changes as they arise. In this context, monitoring using high resolution microseismic techniques will be discussed as a means of providing early warning of such failures.

Jan 1, 2006

By D. Craig Camp

conditions. The soils included 65 m of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2, 130 meters of soft clay, silt, and sand not exceeding 30standard penetration test SPT blows per 300 mm, and 220 m of rock ranging between an UCS of 400-600 kgf/cm2. The river crossing, utilizing 1778 mm OD x 19 mm wall x600 mm steel casing pipe without intermediate jacking stations, was part of a seven kilometer liquefied natural gas (LNG) transmission line in South Korea. This 440-m, 1,442-ft, river crossing was microtunneled through three different ground conditions and completed in just over three months. The crossing was achieved with an average of 25 m of ground cover and 15 m of water cover. The Kwang Yang River Crossing was part of a 7 km liquefied natural gas pipeline project for POSCO, a Korean steel producer. The microtunneling machine was custom built for this project. The microtunneling machine selected for this project was tooled with 7 button bits and 2 roller bits. None of the cutter bits were replaced during the drive. Inside the machine, before the spoils laden slurry was pump back to the surface, it would pass through an independent cone crusher. The crusher is placed in the slurry flow to make sure that none of the spoils are so large as to stop the return flow of the slurry. An additional requirement was for the inclusion of a compressed air lock. The air lock was required in the event that the cutter tools required replacement. The cutters were back loaded so that the workers would have access to change the cutters in the event of cutter failure or wear out. No intermediate jacking stations were installed for the drive. The soils included 65 meters of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2 with production averaging between 7 and 20 mm/minute. The second zone contained 130 meters of soft clay, silt, and sand not exceeding 30 standard penetration test (SPT) blows per 300 mm with production averaging between 80 and 180 mm/minute. The third zone contained 220 m of rock ranging between an UCS of 400-600 kgf/cm2 with production averaging between 7 and20 mm/minute. The steel casing pipe was 1778 mm OD x 19 mm wall x 6000 mm long. The project profile, see Figure 1, shows the soil conditions. The hand written numbers locate just above the pipeline are the production dates. The circled numbers are the 10 pipe joint increments. The project required 74 pieces of pipe to span the440 m drive. Figure 2 and Figure 3 are the jacking information. Figure 3 is a continuation of the information from Figure 2. The top section of the graph is the jacking force. The jacking

Jan 1, 2001

By R. F. Shurtz

The problem of estimating the precision of systematic samples from a mineral deposit is attacked by interpolating the quality, or other attribute measured, by using Fourier approximation. Such approximation using trigonometric functions yields a particularly simple expression for the variance of the mean value of the attribute sampled. The increasing volume of publication in which the science of statistics has been applied to the problem of predicting the quality of an ore deposit from sets of samples taken from it might lead one to believe that engineering judgment can be replaced by statistics. There is, in fact, an implicit application of the principle of indifference or of "no advance knowledge" which has been discredited in modern statistical theory and practice. These pages will show that it is not always advantageous, efficient, or safe to apply this principle. This problem will be dealt with by using series of orthonormal functions to describe the distribution of the quality of ore in space as contrasted with the more commonly used distribution of quality as a frequency function. Mining engineers are rarely well acquainted with the use of such series or of the functions comprising them. These uses are commonplace in the fields of communication and information theory and it is not surprising that applications taken from these fields should be found appropriate for the analysis of the information contained in a set of samples from an ore deposit. It is hoped that presentation of the following basic, but incomplete, results will generate wider interest in this method and a fuller development of it as well as of the necessary computational techniques. FUNDAMENTAL PREMISES Random variables in the strictest sense are not very common in mine sampling. The sets of samples are almost always taken systematically and are, hence, not subject to all the laws governing random events. Therefore, unless there is indeed random experimental error in the determinations of quality, the treatment of systematic samples of n members as though they were random samples of n members often leads to calculation of confidence limits for the mean quality which are larger than they should be with the result that unnecessary additional sampling is done. The reason for this will emerge in the following discussion leading to Eq. 24 and its generalization. In order to inquire into such questions on a rigorous basis and at the same time avoid arithmetic complications that would obscure the concepts involved, a one dimensional distribution of quality will be assumed. The quality, Q, in suitable units is expressed as a function of the distance, x, along some straight traverse of the deposit. Such a function

Jan 1, 1967