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By Jacob Masliyah, Zhiang Zhou, Tshitende Kasongo, Jianjun Liu, Zhenghe Xu, Jeawon Choung

"Slime coating is a recognized challenge in fine particle flotation, not only in decreasing recovery, but also in reducing the selectivity and hence froth quality. In this presentation, a novel method based on electrophoretic mobility distribution measurement to study slime coatings is described. By measuring electrophoretic mobility distribution of individual minerals and their mixtures, the interactions between these minerals can be evaluated.For illustrative purposes, a model system of fine coals, or oil sands with two different types of fine clays was studied. Flotation tests showed a significant decrease in coal (bitumen) flotation recovery with montmorillonite but not with kaolinite clay addition. When electrophoretic mobility distribution of a fine coal/montmorillonite clay mixture was measured, a single modal zeta potential distribution was obtained, in contrast to a bimodal distribution for fine coalkaolinite clay mixture. This finding suggests a stronger adhesion of montmorillonite than kaolinite clays on fine coal surfaces. In the case of bitumen, the bimodal zeta potential distribution was measured for the mixture of bitumen emulsion and kaolinite or montmorillonite, indicating a weak attraction of the clays by bitumen. In the presence of calcium, however, a single modal zeta potential distribution was obtained in the mixture of bitumen emulsion with montmorillonite but not kaolinite clays. These findings are in excellent agreement with bitumen flotation results, demonstrating that the electrophoretic distribution measurement is a powerful tool to study slime coating phenomenon in a complex fine particle flotation system."

Jan 1, 2002

By Godofredo F. Barrios

For years urethane screen surfaces have been used in a wide range of wet screening applications where openings from as fine as 100 microns and coarser have been used. The purpose of this paper is to expose the reader to new developments in both screen surface and screening equipment technologies which allow an end user to consider urethane screen surfaces for fine screening applications. These technologies allow an end user to use the inherent advantages of urethane with regards to wear resistance while also realizing the benefits that a high oper area urethane screen surface can bring. These benefits include non blinding characteristics and feed capacities that which rival that of traditional stainless steel surfaces. The paper will highlight the features of this patented urethane screen surface technology and the screening machines they are used in conjunction with. There will also be a presentation of case studies of commercial installations where these technologies are utilized. These case studies are from the base metals industry therefore relevance to the conference is direct and not inferred. Included in the paper will also be constraints which must be taken into account when considering urethane screen surfaces such as temperature and chemical attacks. This paper will expose potential end users to a possibility of using screens to achieve extremely accurate size separations in applications where screens were previously not considered. The paper will explain and demonstrate that prior concerns of screen surface blinding, high screen surface consumption rates and large screen surface area requirements can be eliminated by proper utilization of high open area urethane screen surfaces.

Jan 1, 2007

By L. Frederick

Measurement of gamma radiation occurring in nature to characterize geological formations has been widely recognized in mineral exploration. Different methods and apparatuses have been developed for drill hole logging purposes. Geological formations vary in amount of naturally emitted gamma radiation. A gamma signature from a geological formation is captured by utilizing different types of gamma detectors. A natural gamma radiation detector (NGRD) can be used to control mining whenever there is a significant difference between the radiation levels in the mineral or ore being mined and the waste materials surrounding the ore. Surface miners, such as the one shown in Figure 1, can precisely control the elevation of the cutter as the machine moves over the surface of the formation. This type of machine is predominantly used in selective mining operations, e.g. surface coal mining. If there is a means to know the position of the cutter relative to the interface between the ore and waste, the miner can recover all or most all of the valuable mineral with very little out-of-seam dilution. This paper discusses the results of a successful application of gamma detectors to control a surface miner at one of North American Coal Corporations? locations - Red Hills Mine. The mine has nine coal seams in total with thicknesses ranging from 12? to 60?. The bottom six seams (Figure 2) are minable. The mine has complex geology and a significant amount of annual rainfall (4.7 ft). The mine produces approximately 3.5 million tons of coal and about 40 bcy of overburden per year. The operation utilizes diverse mining equipment including Dragline Marion 8200, electric shovel P&H 2800, Caterpillar end dump trucks CAT 785 and 789; bulldozers CAT D11, D10, D8, and D6. Coal is mainly extracted by utilizing a Wirtgen SM 4200 surface miner that is loading CAT 785 trucks with high volume coal bodies and payload of 150 t. Operational cutting depth is 24 inches with maximum cutting depth of 36 inches. Surface miner operators determine a cutting depth based on multiple cues, the most important being visual observations of a coal seam being cleaned or mined. The cleaning process involves removal of the last foot of waste material covering the coal seam. This is one of two critical phases in the coal extraction process. If, during the cleaning process, an operator sets a cutting head too deep, valuable product is wasted. If it is set too shallow, waste material is left to be mined with the coal. The second critical phase occurs in the last cut on the interface between the coal and waste material at the bottom of the coal seam. If the cutting head goes deeper than favorable, then waste material is delivered to a power plant.

Feb 27, 2013

By G. R. Robinson

Aggregate resources consist of sand and gravel, and crushed stone. They are large-tonnage, bulk-minable mineral commodities that are used in construction and industrial activities (Tepordei, 1999, 2001).Rates of aggregate production, use and mine permit approval in the mid-Atlantic region differ by population density. These rates are influenced by economic and human factors, such as demand, costs, land availability and community opposition. In some areas, the local availability of aggregate is limited. This is due to the lack of suitable local source materials for aggregate, the loss of potential high-quality aggregate resource production sites by preemptive land development and restrictive zoning (resource sterilization), and the difficulty of developing and permitting production sites for aggregate.

Jan 1, 2004

Fire-clay blocks lining the combustion chambers of zinc concentrate flash-roasting, furnaces operating at 1,000-1,200° C. have suffered moderately rapid deterioration due to slagging. The attack is accentuated by high temperatures, and is probably caused by lead oxide volatilized from the roasted concentrate.Resistance of refractories to attack increased with increasing alumina content from 30 to 45 per. cent but at 90 per cent alumina spalling was troublesome. Magnesite bricks were'subject to some spalling, but some types may lie satisfactory. Chrome and chrome-magnesite bricks spalled seriously.Material thought to be suitable for use as a monolithic lining slagged badly and an alternative may be tested.INTRODUCTIONThe Electrolytic Zinc Company of Australasia Ltd. uses two multi-hearth furnaces and four flash or suspension roasting furnaces for the roasting .of zinc concentrates at its Risdon Works. The hearth roasting plant has been described previously by Forster (1949).A brief descriptioI1 of the first three flash roasters was given by Gordon and Forster (1955). A fourth flash roasting furnace began operation early in 1957. This furnace is somewhat larger than the earlier furnaces, and the designed capacity is also higher, auxiliary equipment being altered to suit. An important structural difference between the older furnaces and the fourth flash roaster is that the walls of the combustion chamber of the new furnace are lined with high alumina fire-bricks instead of fire-clay blocks. Thischange was made because the fire-clay blocks in the older flash roasters had shown s-evere wastage due to slagging by lead derived from the concentrate.

Jan 1, 1959

By S. Atallah

A survey was conducted relating to the current practices for the classification of hazardous locations in coal preparation plants. Several plants processing bituminous, anthracite and lignite coal in Pennsylvania, West Virginia, North Dakota, Colorado, Montana and Wyoming were visited. Coal preparation plant operations and designers as well as MESA inspectors were interviewed. The National Electrical Code was discussed with selected members of the NFPA committee and electrical equipment manufacturers. Data provided by MESA on fire and explosion accidents in coal preparation plants were examined. The requirements of the pertinent Federal Regulations, National Electrical Code, National Electrical Manufacturers Association and Underwriters' Laboratories were compared and evaluated. This report consists of two parts. Part I: "Analysis and Review" provides a summary of the findings. Part II: "Recommended Guidelines" consists of recommended uniform guidelines that may be used for interpreting the National Electrical Code as it applies to the classification of hazardous areas in coal preparation plants.

Jan 1, 1977

Copper waste dump leaching is growing in importance because of the.large tonnages (up to 250,000 ton/day) of low grade waste rock available from open cut mining of copper deposits and proof that controlled leaching of copper from such dumps can be profitable.Overburden or waste rock, ranging in size from large boulders to fines, is dumped as cheaply as possible on sloping sites. Copper is leached from the dumps by applying up to 12,000 gal/min of leach solution (a combination of spent solution from cementation and make-up water) to the top of the dumps by various techniques.Efliuent from the dumps is sent to a cementation plant for copper recovery.Factors which may be controlled, either directly or indirectly, to give a controlled copper content in the dump efliuent (usually 1-2 g/l.) are the cycle of operations (i.e. the alternate wetting and drying periods), thevolume of solution applied to the dump, pH, Fe2+ and Fe3+ content or redox potential, oxygen content, bacteria and their necessary nutrients, and temperature.Dissolution of oxide copper minerals appears to be mainly a function of acid concentration. Copper sulphide minerals need oxidation for dissolution to occur and this is accomplished by a combination of oxygen,ferric ion, and bacteria. Oxidation of pyrite, oxidation of Fe2+ to Fe3 +, and hydrolysis of Fe3+ are of some importance in leaching practice. The presence of gangue carbonate minerals is detrimental.Physical factors connected with penetration of solution into large rocks are important and the treatment of an individual dump usually extends over a period of many years. Recovery of copper from solution is usually achieved by cementation with iron (usually in the form of crumpled cans) but the use of sponge iron is becoming more important. Iron consumption varies from 1 to 4 lbiron per pound of copper. Preconcentration of the copper in the efliuent solution by solvent extraction followed by electrolysis may become a useful method.Application of dump leaching techniques to metals other than copper depends on finding an economic method of recovering the metal from solution...

Jan 1, 1967

By Don McCarthy

Modern mining has been dominated by the drill-and-blast method for more than a century. There have been steady improvements in drilling technology, explosive products, methods of initiation and integration of the two techniques but the essential cyclical nature of drill-and-blast rock excavation naturally limits continuous improvements in cost and productivity. Dynamite and safety fuses, compressed-airdriven tools, and most of the crushing and grinding machinery in use today were all developed before 1900. Moreover, virtually every mechanized mining system used today was in use by the late 1950’s.

Jan 1, 1998

By M. Soleymani Shishvan

"Continuous mining systems containing multiple excavators producing multiple products of raw materials are highly complex, exhibiting strong interdependency between constituents. Furthermore, random variables govern the system, which causes uncertainty in the supply of raw materials: uncertainty in knowledge about the reserve, the quantity demanded by the customers, and the breakdown of equipment. This paper presents a stochastic-based mine process simulator capturing different sources of uncertainties. It aims to quantify the effect of geological uncertainty and its impacts on the ability to deliver contractually defined quantities and qualities of coal, and on the system efficiency in terms of utilization of major equipment. Two different areas of research are combined: geostatistical simulation for capturing geological uncertainty, and stochastic process simulation to predict the performance and reliability of a large continuous mining system.The process of modelling and simulation in this specific production environment is discussed in detail. Problem specification and a new integrated simulation approach are presented. A case study in a large coal mine is used to demonstrate the impacts and evaluate the results in terms of reaching optimal production control decisions to increase average equipment utilization and control coal quality and quantity. The new approach is expected to lead to more robust decisions, improved efficiencies, and better coal quality management.IntroductionContinuous coal mining systems containing multiple excavators producing multiple products of raw materials are highly complex and exhibit strong interdependencies between constituents. A network of conveyor belts is used for transportation of the extracted materials to different waste dumps or the coal stockpile.Optimal decision-making in short-term planning and production control are impacted mainly by geological uncertainty associated with incomplete knowledge of the coal deposit represented in the reserve block model. These uncertainties cause deviations from expected process performance. For more robust decision-making, understanding the impacts of these stochastic elements plays a key role."

Jan 1, 2016

By B. Genc

"The risk of spontaneous combustion is well known in the South African coal mining industry. In the coming years it is very possible that the incidence of spontaneous combustion will increase from current levels, due to factors such as an increased rate of mining, re-working of previously mined seams, more stooping and total extraction for underground mines, and higher stripping ratios for surface mines, leading to more spoils. It is also fairly certain that coal mining will face tougher environmental emissions legislation in the near future. To determine the areas where the risks of spontaneous combustion are high, it is necessary to improve on our current laboratory procedures for testing and evaluating coal samples, combining the results with site and field data, and if necessary revising the laboratory rating system to refine our understanding of South African conditions.Currently, laboratory tests are conducted in order to determine both the Wits-EHAC index and the crossing-point temperature which, when combined, give an indication of the spontaneous combustion propensities of the coal samples. This procedure has enabled the establishment of a database of results to review and evaluate South African coal seams. Using this database, the high-risk areas in terms of spontaneous combustion are identified. Tests have been undertaken for five consecutive years, between 2008 and 2012. In total, 119 coal samples from different coal seams and production coalfields have been analysed and classified through a series of laboratory tests. A comprehensive database of these results is available, and is continually being updated as new test results are added. This database will continue to expand, and to provide the basis for an improved risk evaluation methodology for spontaneous combustion"

Jan 1, 2015

The expansion of hydrometallurgical operations, declining ore grades and upwardly spiralling production increases the demand for fresh and recycled water with low levels of contaminants. The minerals industry is also increasingly being forced both by regulatory and cost pressures to reduce the amount of liquid waste they produce. This requires a strong focus on waste reduction by recycling, regeneration and reuse. However, these measures are often not enough in arid countries for a forward progress and expansion of their mining activities.   It is often the case that in the arid and semi-arid countries the only available water is either sea water or underground (brackish to hypersaline) saline waters. Brackish waters can be desalted at a reasonable cost but the desalination of highly saline waters is challenging and expensive.   There are emerging reports that sea water and in some cases hypersaline underground waters are now used by various mining industries as process water. This study explores the possibility of the use of sea water in various mineral processing and hydrometallurgical processes and briefly discusses the benefits and problems related to the use of saline waters at the mine and mill site. Several cases studies and preliminary laboratory test results are presented.

Jun 1, 2010

By William H. Shockley

THERE was an, extensive mining and industrial exploitation of Russia, about 20 years ago, by Belgian, French and British capitalists; but the results were discouraging. It is said that the Belgian and French public together lost approximately $400,000,000, chiefly in the coal and iron industry of southern Russia. This loss is largely accounted for by the fact that most of the companies were formed, as usual in " boom " times, to sell stock; and that thorough investigations were not made. In 1906, renewed interest was taken in Russian mines, especially in those of gold and copper, and a considerable literature is growing on this subject; but as yet I have seen no account of one of the large Russian mining estates. The following notes on such property, where the conditions are so different from those in the mining regions of the United States, should be of interest This inadequate and probably somewhat inaccurate account is made up, partly from my own notes made on the ground, in the summers of 1904 and 1905, and partly from a volume on the geology and resources of the estate issued several years ago, containing surface-and mine-maps, and from a pamphlet published in 1904, giving a general account of the condition and prospects of the property. This pamphlet includes a report made by Arthur L. Pearse, a member of this Institute, in 1899. Both these books are in Russian, and were prepared by the Bogoslovsk Mining Co., which owns and operates the property. Articles in many other languages have appeared dealing with various matters connected with the estate; but I know of no other general account of it. In numerous books and articles on the Urals and Siberia, however, localities are described in which somewhat similar conditions prevail. Recent papers by

Mar 1, 1908

By H. R. Beard

The Federal Bureau of Mines investigated the absorption of radium and thorium from waste uranium leach liquor by clays and other materials. This work was conducted in support of the Bureau's goal of minimizing the environ¬mental conflicts, impacts, and occupational hazards Associated with mining and mineral processing operations. Tailings and soil samples from Wyoming and Utah were contacted with tailings liquors to determine the degree of absorp¬tion. Absorption ranged from 0 to 99 percent for radium and from 0 to 31 per¬cent for thorium. Some samples, which readily absorbed radium, were contacted with various salt solutions that could be present in tailings solutions to determine their effectiveness as desorbents. The desorption of radium ranged from 0.06 to 100 percent. An alpha-spectrometric method was used to determine the radium and thorium, concentrations in the solutions and the solids.

Jan 1, 1979

The mineralogy of the rocks now observed in the Nairne pyrite deposit developed under conditions of internally-controlled sulphur activity during amphibolite facies metamorphism. In the sulphide-deficient metasediments the activity of sulphur was low, and pyrrhotite developed with iron-bearing silicate minerals. At higher sulphur activity, in the sulphide-rich meta-sediments, pyrite formed in addition to pyrrhotite, and the associated silicate minerals are iron-deficient.

Jan 1, 1969

By P. Quinn

"The Venturi-aerated flotation column (VAC) is based on a reactor and separator design for a new generation of flotation machines. The reactor is a Venturi tube, where the air/slurry contact takes place with intensive aeration for efficient particle collection. The separator is a column of 1-3 m length that provides quiescent hydrodynamic conditions for effective separation of bubble-particle aggregates from the remaining slurry.Aeration in the Venturi tube occurs via two mechanisms: air dispersion and nucleation (cavitation). By forcing air through a restricted passage with a fast flowing slurry stream, air is dispersed into fine bubbles. Bubble formation due to cavitation occurs on the surface of particles in the low-pressure section of the Venturi, from dissolved air contained in the liquid.Size-by-size recovery and flotation rate constants were determined for a small-scale laboratory Venturi-aerated flotation column. The results were compared to those obtained in a laboratory 2.2 L Denver cell. It is shown that the Venturi-aerated flotation column has slightly slower flotation kinetics to the Denver cell, but with much higher flotation selectivity. A portable Venturi-aerated flotation column can effectively be used to investigate process or equipment problems in operating plants.INTRODUCTIONFlotation processes can generally be divided into two sub-processes: 1) selective collection of hydrophobic particles by air bubbles and 2) separation of bubble-particle aggregates from hydrophilic particles that remain in the pulp. The methods of aeration, or bubble generation, control the mechanism of particle collection by either collision with, and subsequent attachment to bubbles, or by in situ bubble formation on the surfaces of hydrophobic particles. A flotation device should provide optimal aeration conditions for efficient particle collection and a suitable hydrodynamic environment for effective removal of bubble-particle aggregates from the remaining pulp."

Jan 1, 2002

William Frederick McBryde Broun, a graduate of the Royal School of Mines, was employed on the staff of the Mount Morgan Gold Mining Company for some years prior to 1912, and will perhaps be remembered by some of those who attended the Mount Morgan meeting of the Institute in 1910, as an Associate Member present on that occasion. He severed his connection with the Mount Morgan Company in 1912, and was returning to England via the East Indies, when he contracted typhoid atSingapore and died at Colombo.Years later some old papers were being turned out in the office where he had worked, when a set of M.S. notes in his unmistakeable handwriting came to light. On examination these appeared to be the rough draft of a paper he must have beenpreparing for the local branch of the Institute, which he had not been able to complete. The notes were very rough. Apparently it was the author's intention to fill in numerous gaps with extracts from sundry published articles on Cornish mining; theextracts were missing and only the written portions linking them together were there. They give a sketch of Cornish mining practice which those who wish may supplement (as the author would have done) from Le Neve Foster and other well-knownsources. The fragmental notes which have been pieced together as carefully as possible by Mr B G Patterson, Hon Secretary Mount Morgan Branch; are as follows :-The first mine the author worked at was Carn Brea, in 1904."This is one of the largest tin mines in Cornwall, and belongs to the Carn Brea and Tincroft Mining Co, which also owns Cooks Kitchen. The mine was started in 1832, but had been in a bad way for several years previously, and had just begun to recover...

Jan 1, 1919

By Charles E. Wait

It is said by some that the occurrence of a deposit of sulphide of antimony in Southwestern Arkansas has been known for fifteen or twenty years. Whether or not such is the case I am not prepared to say, but I am not able to find any record of such a discovery, or any analysis of antimony ore obtained from that section, published at so early a period. The present discoveries, that seem to be attracting some attention, date back to the winter of 1873-74. At that time a vein of ore was found by Mr. Robert Wolf, in honor of whom the vein was named, and still is called, "the Wolf lode." At the time of the discovery the ore was unknown to the prospector, and its composition was not thoroughly understood in that locality until samples were sent to several analytical chemists, who pronounced it sulphide of antimony—stibnite. Since the discovery of this ore there have been three mines opened, and a number of interesting minerals of the antimonial series have been found. I have had an unusually good opportunity to collect specimens from these mines; and it is owing to the constant inquiry concerning the character of these ores that I have collected for publication the results of quite a number of analyses, sufficient I trust to clearly point out their composition. This is one of the few localities in the United States where antimony ore is found in workable quantities ; I say workable quantities, because two different shipments of ore have been made to English reduction works, and in both cases excellent returns were made. The discovery of these deposits will, it is hoped, give rise to a prosperous and remunerative industry at no distant day, and when fully developed they may yield ore in sufficient quantity to supply the regulus for the home demand, thus adding wealth not only to those interested, but also to the State of Arkansas. The three mines are situated in the northern part of Sevier County, and may be reached by the St. Louis, Iron Mountain and Southern Railway to Fulton, thence by wagon-road to Columbus, Nashville, Centre Point, and to the mines. During most seasons of the year the

Jan 1, 1880

It is shown that factors associated with conditions whIch are thermodynamically favourable for the formation of CuS04 in roasting lead to high copper recoveries on leaching. One of these factors is the ratio of the air to solids used for roasting. This can be varied widely without loss of temperature control in the sulphating roasting of many Australian copper concentrates.Thus, the prediction of the air to solids ratio corresponding to a maximum p(SO3) value, for a given concentrate and temperature, is of importance in fluidized bed roasting, since this could be associated with the formation of a maximum quantity of CuS04. Calculations are presented which predict this air to solids ratio, not only for a given concentrate composition, temperature, and pressure, but also for air which is enriched with sulphur dioxide or oxygen.

Jan 1, 1968

By John C. Nigro

Bench scale and pilot plant research was conducted using dolomites (CaO,MgO) lime as the basic additive in the preparation of self-fluxed pellets from a typical magnetic taconite concentrate (5.57 S_2). The specific objective of this investigation was to ascertain the viability of the magnesia lime pellets in high temperature oxidizing and reducing atmospheres. Pellet basicity and induration temperature were major parameters affecting fired pellet quality; temperatures ranging from 1,200° to 1,250" C appeared to be the most favorable for production of self-fluxed pellets with basesities (B) above 1.0. Comparison of the mechani¬cal and metallurgical properties of regular (acid) and self-fluxed pellets (B 1.55) produced under similar conditions in a modified grate pelletizing machine showed that the self-fluxed pellets were more resistant to abrasion and to high and low temperature reduction disintegration, an important consideration in commercial application. The Plus 3 mesh Linder index increased from 68 percent (regular pellets) to over 90 percent (self-fluxed pellets). The reducibility and swelling indices of the self-fluxed pellets were found to be comparable to the regular pellets.

Jan 1, 1972

By McKenzie P

The techniques of geological control developed by the Coal Geology Sections of the Broken Hill Proprietary Company Limited and Australian Iron and Steel Proprietary Limited in providing geological service in the coilieries operated by these associated companies cover the provision of geological control for both planning and production in each of which the significance of geology has in the past been only poorly appreciated by the coal mining industry.While the adoption of similar techniques is well within the capacity of major companies there is considerable scope for the development of government geological services providing specialized assistance of this nature for smaller scale producers.INTRODUCTIONThe coal mining industry in Australia can instance many notable mistakes caused by failure to obtain sufficient geological information or by incorrect interpretation of available geological evidence both before the commencement of mining and during the progress of operations. Substantial development undertaken in, areas with insufficient or inferior coal reserves, difficult mining conditions caused by failure to adjust operations to geological circumstances, and the irregular development of mine workings caused by unexpected geological features, all bear witness to the lack of geological foresight by the industry.Along with the more widespread general use of applied geology, an increasing acceptance has developed during the past ten years of the valuable contribution which can be made by this science to the exploitation of coalfields. In spite of the advances which have been made, there is still a wide scope for further detailed application of geology throughout the coal mining industry in Australia.

Jan 1, 1963