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By R. G. Gillies, C. A. Shook, W. H. W. Husband

"The current state of knowledge concerning pipeline transport of coal in water slurry form is summarized for the four categories: coal-water fuels, conventional fine coal slurries, coarse coals and stabilized mixtures of coarse and fine particles. Surface chemistry is of dominant importance for coal-water fuels and considerable progress in understanding the role of surfactants has been achieved in recent years. Little generalized research on the flow of conventional fine coal slurries has been done in the past 17years, although innumerable conceptual designs and feasibility studies have been undertaken. Coarse coal slurries are fairly well understood but the model which explains their flow requires more data to be established fully. Stabilized flow mixtures should probably obey the same model as coarse coal slurries but experimental results for stabilized mixtures have not yet been incorporated in a comprehensive theory.IntroductionPipeline transportation of coal in a water vehicle has been employed for many years in coal washeries. It has been used less frequently in hydraulic mining and thermal power station fuel supply systems. The suitability of coal for pipeline transport arises from its moderate specific gravity relative to the carrier fluid and the fact that throughputs are often large and steady over long periods of time."

Jan 1, 1990

By R. P. Taylor

"This paper covers the development of the property to its present production level of20,000 tonnes per day from the Valley Mine. It will also review the analysis of various case studies for the expansion of the project to its full potential, and discuss the impact of the recent structural change in the copper market on the development of a large low-grade deposit such as Valley.IntroductionIn 1964 Cominco participated, along with a number of other companies and individuals, in the formation of Valley Copper Mines Ltd. This company was formed in order to facilitate exploration on a large number of mineral claims held by these parties in British Columbia's Highland Valley, approximately 400 km northeast of Vancouver (Fig. I). Cominco 's ownership of Valley Copper was gradually increased over the years bot h through shares gained for exploration expenditures and through shares purchased on the open market. By the mid- 1970sCominco' s interest in Valley Copper exceeded 80%.ExplorationExploration from 1964 to 1969 led to the discovery of a massive porphyry copper depo sit now known as the Valley orebody. A claim boundary divided the deposit with 80% of it on Valley Copper claims and 20070 on claims held by Bethlehem Copper which was already mining adjacent copper orebodies. During the period when the Valley ore body was discovered, exploration by other companies resulted in the discovery of the large Lornex and Highrnont deposits nearby. The stage was now set for the Highland Valley to become an important copper-producing area (Fig. 2)."

Jan 1, 1986

By Chaluvadi K. Sridhar, Prashanta K. Chatterjee

"IntroductionThe planning of an underground coal mine requires a complex blend of technical expertise, experience and subjective design criteria implemented by the mining engineer. Currently the procedure is largely manual and requires considerable resources to generate a single mine plan. Often three or four people are assigned to work in the development of a single draft layout. Evaluation of the layouts is also tedious as it requires many repetitive calculations. The evaluation of layouts developed manually generally attempts to derive a single economically feasible solution. Operational constraints in underground coal mining such as manpower, time, equipment, etc., do not allow the generations of more than one alternative layout. As a result, the first plan is generally the only one considered.Computer-aided mine planning can automate many of the manual procedures and calculations involved in mine planning thus allowing to evaluate man y layouts and mining strategies and to select the optimum plan with confidence. An optimized planning procedure will also provide the capability to evaluate mine performance continuously and critically, thereby helping to maximize return on investment. Although recent advances in computer graphics have provided the hardware necessary for developing and evaluating min e plans rapidly, software that will allow the mining engineer to make use of the new technology is slow in developing. The need for such software packages has been recognized and ackowledged.At several sessions in recent conferences on the applications of computers in the mining industry, the use and benefit s of computer-aided mine planning were discussed. However, there were few papers presented that referred to actual applications of interactive graphics to underground mine planning. The emphasis of this study is toward the development of a completely integrated computer-aided underground mine planning package that integrates geological modeling, engineering design and planning"

Jan 1, 1986

By R. F. Engler

"IntroductionThe Coal Branch region of west-central Alberta has been the focal point for unprecedented exploration and development activities over the past ten years prompted by the renewed markets for high-quality thermal coal. Although mines were developed and operated extensively throughout the region from 1910 until 1960, information relating to the detailed stratigraphy of the coal measures and their areal distribution tended to be localized to individual mine sites. Continuity along trend was impaired by a paucity of outcrop restricting geologic mapping to stream bank and roadside exposures. Recent studies and subsequent publications by Jerzykiewicz and McLean of the Geological Survey of Canada (1978, 1980) have established a detailed sedimentological model and defined the stratigraphic nomenclature for the region . The term Coalspur Beds has been adopted to describe the coal-bearing sequence between the overlying Paskapoo Formation and underlying Brazeau Formation. Complete sections of the Coalspur Beds have been compiled from sub-surface borehole data and published by Manalta Coal Ltd ., Dentherm Resources Ltd. and Luscar Stereo Ltd. This paper is an attempt to correlate this information on a regional basis to illustrate trends within the Coalspur Beds."

Jan 1, 1986

By J. C. Thornley, H. L. J. Drummond

"Fifty years of wear on the original carbon steel shaft of this hydro turbine necessitated repair operations in 1980. Both austenitic and martensitic stainless steels have been used individually as journal materials in separate trials on an80-inch long and 22-inch diameter radial bearing but neither one nor the other has been successful.The wear and cracking problems of the stainless steels leading to the present abandonment of both classes of stainless steel are described. In particular the dependence of the toughness of type 410 stainless steel on its tempering temperature and the susceptibility of that steel to quench cracking are highlighted because problems have been caused by both of these metallurgical factors.IntroductionAs part of a desire to improve the efficiency of a fifty-year old hydro-electric generating station on the Saint John River, the decision was made to change the journal and bearing material for the shaft bearings, which are stave-type bearings. For the initial fifty years of operation the bearings had been wooden (lignum vitae) and had run on the carbon steel shaft directly. For one of the four unit s at this station the performance of this combination has been truly excellent, and the remaining three sets of bearings had performed well. However there had been shaft wear on the units and the wear had made the shafts somewhat elliptical when a decision was made to install some sort of new journal on to three of the old shafts. [In addition to the wear on the carbon steel journals it was found that one shaft was significantly softer in the bearing area than it was immediately above the bearings (180 Vickers in comparison with 230 to 250 Vickers)] ."

Jan 1, 1985

By Robert J-M Ethier

"Sequential blasting has been introduced at Mines Gaspe to reduce the harmful effects associated with the instantaneously primed blasting method. Three stages of modifications had been tried to improve this method: trials of a rectangular pattern instead of the square one, trials of lengthened hole collars at the perimeter of the blast and trials of increased inter-row delay intervals from 35 to 50 ms. Results showed that improvements to the instantaneously primed blasting method were limited by the probability of increasing the number of bootlegs.Doing these modifications allowed the definition of a general approach to improvements before the sequential blasting method was introduced. This general approach included: planning of the mining sequence, following up on the drilling, loading and tying-in of each blast, compiling and evaluating blast results, comparing results from one bench to the other and moving along with one change at a time. This approach has permitted the successful introduction of the sequential blasting method in two steps: trials of blast by rows of delayed holes and trials of hole-by-hole blasts. The optimum result has been analyzed by high-speed camera and by computer blast simulations, The actual optimum sequential blast is obtained with a CORDLINE priming system using period 15, permitted in a large drilling pattern, with an intersequences delay interval of 230 ms and an inner-sequences delay interval of 50 ms.While these modifications were being introduced, a careful study of the drilling and blasting costs was made, which showed a sharp reduction of drilling cost per tonne. Even though there was an increased use of packaged slurry the blasting cost per tonne also dropped. The reduction in cost per tonne was explained by the fact that the average energy factor was maintained while the blasting pattern was expanded.The sequential blasting method, successfully introduced at Mines Gaspe, permits blasts of better quality, reduces the drilling requirements by more than 30% and helps to achieve improved productivity while minimizing costs."

Jan 1, 1984

By R. J. Mitchell

"Centrifuge modelling of earth structures is a well-proven technique for evaluating the performance of prototype structures using physical models. The applications of this technique have increased dramatically during the last decade such that even the modelling of dynamic responses in structures has been accomplished.This paper presents the first model test results used to design a mine backfill. The models were tested using a 3 m radius 30 g-tonne geotechnical centrifuge which was constructed at Queen's University specifically for model studies on mine backfill stability and subsidence. The models represent the first production blast-hole stope to be mined at Westmin Resources Ltd. 's H. ~ Mine on Vancouver Island. This paper includes photographs of:model failures in the centrifuge and correlations of model test results with analyses based on unconfined and triaxial test data.IntroductionDuring the feasibility study and development stages for the H.W. Mine, Westmin Resources Ltd. conducted a comprehensive rock mechanics and backfill engineering program. The results of these studies indicated the need for assurance of backfill stability during pillar recovery on the initial blast-hole mining block. The cemented tailings backfill had to be free standing for heights up to 25 m and the potential for surcharge loading from a weak hanging wall zone, the potential for fill block sliding down-dip and the potential for seismic loading had to be considered in the design of the fill strength. The basic questions to be answered were: what cement content is required and will the resulting backfill costs be economic relative to the proposed mining method and sequence? Figure I shows a typical cross-section through the first mining block . The up-dip stope is to be mined first and backfilled with cemented tailings . The down-dip stope would then be mined and filled. Depending on ground conditions encountered, the complete intervening pillar could be recovered and the void backfilled with uncemented tailings or it could be recovered in small sections by exposing limited back and wall areas, backfilling with waste rock and I or cemented tailings . This latter method is commonly referred to as the Avoca method"

Jan 1, 1987

By R. K. Singhal

"On the mining side the Canadian oil sands industry has become proficient in excavation and disposal of ore and overburden. Nearly twenty years of mining experience is now behind this industry. While local improvements to existing mining systems and practices will continue, it is believed that some further gains in productivity can be achieved by selectively introducing new ideas from other mining and non-mining industries. This type of technology transfer is vital for over-all cost-effective technology enhancement of oil sands mining operations.Discussed in this paper are the issues of mining equipment, equipment sizing, microprocessor and computer based technol¬ogy as applied to mine-wide data management, automation and remote control and a projection of likely mining systems in the year 2000!This paper reviews the ""state-of-the-art"" in selected surface mining systems and attempts to evaluate the forthcoming technology and its application."

Jan 1, 1989

By Bern Klein, A. Tugba Cebeci, Libin Tong

"Sensor based sorting faces two main challenges related to limited capacity/throughput and the ability of sensors to accurately discriminate based on estimated grades. This paper is aimed at improving sensor discrimination. Sensors have the ability to measure more than a single response. X-ray fluorescence (XRF) can detect and provide concentration information about a range of elements. Similarly, electromagnetic sensors (EMs) can generate magnetic susceptibility and conductivity responses over a range of frequency levels. The sensors thereby provide a response signature rather than a simply a single response that is a proxy for a metal grade. Furthermore, integrating sensor responses can improve the discrimination of metal bearing rock from waste. A study was conducted on a gold ore to assess sortability using XRF and EM sensors. A multi-variable regression approach was used to develop models that included a range of responses. Correlations improved significantly when compared to single response correlations. The approach showed that both positive and negative correlations contributed to the improved correlations. Stepwise regression simplified the models and showed that 2nd order interaction effects can be important. The approach also showed that combining different responses can improve discrimination accuracy. An important outcome of the study was that an ore that had been consider not to be sortable was determined to be sortable through the application of an approach that used the sensor responses in a more intelligent manner.INTRODUCTIONMining is aimed at recovering valuable minerals from their host rocks. Many methods are used to recover valuable minerals, and finding efficient and cost-effective ways is the key in research and production. . Ore sorting technology is fitting this definition. It not only discards waste rocks away from the concentrator but also recovers metal bearing ore particles that could be lost to the waste dump. The benefits of ore sorting include increased energy efficiency and reduced water and reagent usage in the downstream operations (Bamber, 2008; Gunson, Klein, Veiga, & Dunbar, 2012; Mazhary & Klein, 2015; Robben, Wotruba, Robben, von Ketelhodt, & Kowalzcyk, 2013)."

Jan 1, 2016

By Vlad Ruzicka

"Uranium deposits in the Rabbit Lake-Collins Bay area are associated with the sub-Athabasca unconformity which separates crystalline Archean or Aphebian basement rocks from Helikian clastic sedimentary rocks of the Athabasca Group. The basement rocks are a part of Wollaston lithostructural domain.Most of the high grade deposits, such as Collins Bay ‘A’ and 'B' Zones and Eagle Point are associated with altered rocks of the basal unit of the Wollaston Group. Some deposits, such as Raven and Horseshoe are confined to the uppermost unit of this Group. The Rabbit Lake deposit occurs in the middle, meta-arkose unit of the sequence. Locations of some deposits (Rabbit Lake, Collins Bay ‘A’ and 'B' Zones) are also controlled by thrust faults, such as Rabbit Lake Fault and Collins Bay Fault.The deposits contain either monometallic (uranium) mineralization (Rabbit Lake, Raven, Horseshoe) or polymetallic (mainly uranium-nickel) assemblages (Collins Bay “A’ and 'B' Zones).IntroductionThe Athabasca Basin region, a part of the Churchill Geological Province of the Canadian Shield, is composed of Archean and Aphebian crystalline basement and younger, Helikian, unmetamorphosed supracrustal rocks. The Rabbit Lake-Collins Bay area is situated at the eastern margin of the Athabasca Basin region, which hosts a substantial proportion of Canadian uranium resources.The crystalline basement complex was subdivided by Lewry and Sibbald (1979) into lithostructural domains and these domains were grouped into major crustal units designated, from northwest to southeast, as Western Craton, Cree Lake Mobile Zone, consisting of Wollaston, Mudjatic and Virgin River domains, and Rottenstone Complex (Fig. 1)."

Jan 1, 1986

By Robert B. Parsons

"This month, Tax Notes focuses on two features which can potentially ""dress up"" a new issue of common shares to make the shares more attractive to investors. Attaching warrants to a share issue is a relatively common practice, and recent years have seen an imaginative variety of different kinds of warrants, some of which can be subject to somewhat different tax treatment . A less common financing strategy which certainly deserves some consideration involves the possibility of utilizing ""Share Purchase Tax Credits "" in conjunction with a new share issue.IntroductionPrevious subjects covered in Tax Notes have dealt with flow-through shares and other tax angles which can make equity issues more appealing to potential investor s. Two other techniques which can add zest to a new stock issue involve the utilization of warrants and ""share purchase tax credits"" (or SPTCs). This article takes a brief look at the better known subject of warrants and the lesser known matter of SPTCs.Of course, this paper presents only a relatively general summary of the income tax implications of warrants and SPTCs, and is not intended to be a definitive commentary on all of the detailed and complex tax issues that might be relevant in the circumstances."

Jan 1, 1985

By M. C. Villeneuve, P. A. Siratovich

We present an integrated analysis of laboratory-based thermally induced fracturing and results of numerical models to give insight to the role of thermal shock fracture on geothermal reservoir rocks. Thermal stimulation is a reservoir permeability enhancement technique applied to commercial geothermal reservoir rocks to enhance fluid injection capabilities for spent power plant working fluids. The process is well known to enhance permeability but the thermodynamic and physical constraints of the process are less certain. In an attempt to constrain the interaction and the ideal conditions that lead to permeability enhancement, experimental procedures were carried out to mimic the conditions that a reservoir rock would experience during a thermal stimulation using temperature differentials ranging from 50-300°C. Samples underwent such thermal gradients under controlled laboratory conditions and were characterized for the changes to permeability, porosity, ultrasonic velocities, dynamic elastic moduli and petrological changes. The thermal stimulation was simulated in a FLAC2D thermal numerical model to investigate the nature of the thermally induced changes in the sample. The development of this model also allows us to investigate the relationship between geological characteristics and the ability to thermally stimulate any type of rock. The results indicate that numerical thermal shocking experiments are corroborated by laboratory-based results. The implication of this study is that the refined numerical models present an insight to the conditions and constraints under which thermal stimulation can prove to enhance permeability that could not be gained through purely laboratory-based studies.

Jan 1, 2015

By O. E. Humeniuk, A. I. A. Salama, M. W. Mikhail

"Performance testing of prepartion plants is referred to as plant audit. It evaluates plant performance under normal operating conditions and is aimed at improving yield through knowledge of actual process performance and interactions between different processes in a plant.This paper describes the program to evaluate the performance of several Canadian preparation plants. The performance test requires the planning of a sampling campaign that would include all circuits in the plant. Samples are analyzed to determine washing characteristics (screen and float-sink), ash and per cent solids of feed and products of separation units in the plant. Performance characteristics are established based on analysis and material balance. Specific recommendations can then be made to improve recovery, and identify and explain potential causes of apparent deficiencies.The objectives of the program are to reduce the cost of production by improving recovery of clean coal and, in tum, to reduce disposed tailings, establish baseline information on coal preparation plants performance in Canada, and define R&D work needed to optimize plant operation."

Jan 1, 1993

By J. P. Aiello

"INTRODUCTIONWhile this paper deals specifically with potential coal use at the Cold Lake Project of Esso Resources Canada Limited, a majority of the technical aspects of coal conversion could apply to any oil field and industrial boilers or stearn generators. In 1962, Imperial Oil Limited's production arm (the forerunner of Esso Resources), began examining methods of extracting bitumen from a 50 m thick layer of oil sand buried 450 m below the surface in the Cold Lake area. Almost two decades of research followed to develop an in situ oil sands recovery technology that made commercial production feasible.A $13 billion mega project that would have produced 22 000 m3/d (141 000 barrels/day) of synthetic crude oil (160 000 bpd of bitumen) was shelved in 1981, and ultimately replaced by a phased development strategy, involving smaller production units, to bring blended bitumen production on stream as markets and prices permit.The first two phases came into production in 1985. There are currently a total of six phases in production with four more in the construction stage. Each phase has 130to 140production wells (initially) and a central plant with water treatment, crude treatment and stearn generating facilities capable of producing 150 m3/d (9500 bpd of raw bitumen). The stearn generation section for each phase consists of three 180millionBtulhour oil fieldsteam generators.In its natural state, the bitumen is too thick to be recovered using conventional oil recovery techniques. At the Cold Lake Project, bitumen is recovered by a method called cyclic stearn stimulation. Water is pumped to the central plant where it is treated and heated to produce high pressure, high temperature steam. During the steam cycle, this steam is transported in insulated pipelines to the wells for injection into the oil sand formation. This cycle lasts from 30 to 50 days, heating the formation and causing the bitumen to flow. Following an initial flowback period, a surface based artificial lift system pumps the heated liquid bitumen, mixed with water and gas, out of the well and back to the central plant. The water and gas are separated from the bitumen, with the gas being used to provide some of the fuel for the stearn generators and the water being treated and recycled. Approximately 5% of the water cannot be recycled and is disposed of by injection into deep formations . The bitumen is blended with a diluent and shipped by pipeline to market."

Jan 1, 1989

By Anna Szostak-Chrzanowski, Adam Chrzanowski

"New techniques in monitoring surveys and new methods in the analysis and prediction of ground subsidence are being developed in the Department of Surveying Engineering at the University of New Brunswick (UNB). The new surveying techniques include a telemetry monitoring system developed at UNB in cooperation with CANMET, and use of the satellite Global Positioning System. A generalized approach to the analysis of deformation surveys has been developed which permits an integrated analysis of geodetic and geotechnical measurements in geometrical modelling of ground subsidence. A computer program, FEMMA, has been developed for the elastic and non-linear elastic analysis and the deterministic prediction of deformations using the finite element method.IntroductionResearch and development of new monitoring techniques and new methods in the analysis and prediction of ground subsidence in mining areas is an integral part of a broad research program on deformation surveys which is being carried out in the Department of Surveying Engineering at the University of New Brunswick.The research concentrates on:developmentof a general method for predicting deformations with an emphasis on the use of the non-linear elastic finite element analysis; development of a generalized approach to the geometrical analysis of deformation surveys with an integration of geodetic and geotechnical measurements; and development of new monitoring techniques with an emphasis on continuous data acquisition and application of new space techniques such as the satellite Global Positioning System (GPS).This paper gives a brief report on the progress and recent developments within the above program."

Jan 1, 1987

By G. R. Guillet

"Bricks made from local Paleozoic shales, and floor and wall tiles made from imported clays, both established record production volumes in 1985 and are the strongest segments of Ontario 's clay products industries. However, renewed interest in traditional materials also supports a good market for clay flower pots and flu e liners, and innovative processing studies are showing promise for possible new production of clay roofing tiles. This paper reviews the highlights of a comprehensive study of Ontario's clay products industries, completed in 1986. IntroductionFor some years now, Ontario' s clay products industries have been unspectacular in their attempt to cope with the recent recession and the impact of alternative materials. But a strong demand for bricks in recent years has done much to dispel the gloom.Bricks, drainage tiles, sewer pipes, flue liners, structural and partition tiles, and flower pots have been commonly referred to as ""heavy"" clay products, and they have been based largely on local clays and shales. To this list might be added expanded aggregate and mineral wool. Clay refractories, sanitary ware, electrical porcelain , art pottery, and floor and wall tiles are not considered heavy clay products, and are commonly made from a variety of ceramic materials, many of which are imported.Production facilities for heavy clay products often began in Ontario as small family enterprises, using whatever clay was available locally to supply the local market with building bricks and other clay products needed for construction. Improved road systems increased the market range for these plant s, and new technology and industry standards resulted in gradual"

Jan 1, 1988

By Grant L. Anderson, Richard C. Rice, Richard L. Jentgen

"Data for underground mine-hoist ropes determined in the Ontario Special Rope Tests were obtained, encoded and analyzed statistically. Prior 10 refined statistical analyses, these data were subjected la characterization studies and preliminary analyses to allow trends to emerge that could be used to guide and facilitate the refined analysis. The data were characterized by determining distribution s for a wide range of variables including remaining strength, service life in terms of lime and hoisting cycles, outer-wire torsion values, elongation during tensile testing, diameter reduction, location of strength loss and the strength lasses associated with corrosion rating and lubrication rating , This paper describes the more important relationships between remaining strength (or, conversely, strength loss) as the dependent variable and some of the principal independent variables mentioned above.IntroductionBoth productivity and safety in underground mines could be improved if mine-heist rope Iife and reliability could be predicted more accurately . As a result, hoist-rope failure processes and their effects on rope life and remaining strength need to be quantified and related in such a way that improved retirement criteria can be developed. This is true whether the failure is incipient or actual or whether the failure mode is by corrosion , wear, fatigue or a combination of these factors."

Jan 1, 1984

By J. Stiksma, R. Kalanchey, M. J. Collins, G. Owusu, R. Raudsepp, K. R. Buban, L. A. Barta, L. Masters

This paper describes the results of testwork for the treatment of Ambatovy laterite by an acid pressure leach process, with recovery of the soluble nickel and cobalt values as mixed sulphide intermediate by precipitation with hydrogen sulphide, and subsequent refining of the mixed sulphide to nickel and cobalt metals. These process development studies were carried out primarily in 2004, as part of a bankable feasibility study for the Ambatovy Nickel Project.

Jan 1, 2004

By G. R. Heffernan

"In the early 1970ssteelmakers worldwide were looking forward to many years of expansion and profitability. Huge government investments in Europe, the United Kingdom, Japan, Brazil, and Venezuela were committed in anticipation of growing market s based on long-term OECD forecasts. In 1973 the first OPEC oil shock occurred. Steel demand shrank. Restructuring became the buzz word of the day as billions of dollars in taxpayers' money was poured into eliminating excess capacity and labour. In the United States, where government help was not available, inefficient companies went bankrupt; capacity was cut to 100 million tons from 155 million tons. The industry throughout the industrialized world shrank. By 1979the world economy seemed back on track and a modest degree of optimism could be detected in the international steel fraternity. Then came the second oil shock. By 1982 the industry was in the midst of another shakeout. More bankruptcies, more rationalization, and fewer jobs resulted. In Canada some well-known companies came close to the brink as low prices and high interest rates took their toll. In the light of the turmoil in the steel market over the past 20 years an attempt to forecast the trends through to 2001 is intimidating.However, there are good reasons to be optimistic today about both markets and technology.An economic super power is emerging in western Europe as 1992 draws near. The creation of a single market of 320 million well educated and economically ambitious people has major positive implications for steel demand. The mega projects of the channel tunnel, a European network of high speed railways, and the London docklands are the forerunners of greater things. Still to come is another $200 to $300 billion by the year 2001 in identifiable major projects for highways, railways, airports, water and sewage systems. Add to that the demands of an increasingly affluent population for automobiles, appliances and housing. On top of all that place large increasing demands for electric power and you have a potential beyond anything seen during the 1970s and 1980s. In 1988 the EEC steel industry operated at 90% and in 1989 at 92% of effective capacity. A surge in spot prices indicated that 92% was close to the ceiling. This pace moderated in early 1990 but any slack will probably be taken up rather quickly."

Jan 1, 1990

By E. I. Vargha-Butler

The determination of surface tensions and contact angles of coal particles is of great interest for coal beneficiation processes such as froth flotation and oil agglomeration and for the inclusion of coal particles into oil droplets as a means of enriching the fuel. Methods for contact-angle measurements on small irregularly shaped solid particles have not been available in the past. Therefore, we recently developed a novel technique to determine contact angles and surf ace tensions of coal particles. Two types of bituminous and one type of subbituminous coal particles have been tested. The technique used is called the freezing-front technique and it considers the behaviour of the test particles (in the range of 20-250 pm) at the solidification front of carefully selected, well-defined solidifying melts (matrix materials) such as thymol, biphenyl, naphthalene, salol and 2-phenyl phenol.The results show that the technique works well, providing quantitative and detailed information on the wettability of coal particles. The sensitivity of the method is so high that a difference in contact angle of approximately 4 degrees between the smaller and the larger particles is clearly registered.

Dec 1, 1981