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By Z. D. Hora

Commercial production of barite commenced in British Columbia in 1940; shipments have been recorded from ten deposits, of which four are particularly significant: The Brisco, Silver Giant, Parson, and Mineral King mines. Parr of the barite production is a by-product of base metal deposits in which barite is a major gangue mineral. About one hundred occurrences are known. COMMERCIAL production of barite in British Columbia dates back to 1940. Production volumes rose and fell and reached 39,900 tonnes in 1972. The main producer is Mountain Minerals Limited . There are two principal areas of barite deposits in British Columbia: ( I) The southeast part of the province along the Rocky Mountain Trench , which is the source of all production to date. (2) Stratabound occurrences in northeast British Columbia in the Gataga-Ketchika rivers and Muncho Lake areas which are not yet developed. Of the approximately one hundred reported barite occurrences, only ten have recorded commercial shipments, some of insignificant amount. So far, four deposits have proved to be important producers: Brisco, Silver Giant, Parson and Mineral King. The Mineral King property is situated near the confluence of Toby and Jumbo Creeks, 35 km southwest of lnvermere. The lead-zinc-copper-iron-barite deposits, as described by Fyles (1959, 1962), replace Proterozoic Mount Nelson dolomites of the Purcell system on the limb in the trough of a complex, tight syncline. The mine operated from 1954 to 1967 and 2,097,900 tonnes of baritic ore that was processed for base metal concentrates and also produced 22,680 tonnes of by-product barite. Since 1970, some 136,000 tonnes of barite have been recovered from the old tailings pond. The deposit is now considered depleted. The Silver Giant mine is located 10 km northwest of Spillimacheen. Barite and lead-zinc sulphides replace Cambrian Jubilee limestone near their contact with the overlying Ordovician McKay slate. Mineralization is located in the nose of an overturned plunging anticline. Between 1951 and 1957 800,000 tonnes of baritic ore were processed for lead and zinc concentrate. After 1959 barite was also produced , first from open pit, and later from reworked tailings. Up to 1979 production of barite totalled approximately 180,000 tonnes. Two other producing mines in the area are descri bed by G.R. Manson (this volume). Large, bedded stratabound barite deposits are reported from northeastern British Columbia. Six major shale-hosted Industrial Minerals in Canada lead-zinc-barite occurrences are known in the Devonian Gunsteel Formation. These are: Driftpi le Creek, Mount Alcock, Cirque, Pie, Fluke and Elf. In addition, numerous occurrences of strati form blebby or nodular barite and locally massive white crystalline barite are known from the Driftpi le Creek and Ak ie River districts in Gunsteel shale and from the Kechika, Road River and Ware map areas from Silurian siltstone . The size of these deposits is impressive; the baritic horizon at Mount Alcock is reported to be 25 to 30 m thick , and dri ll ing results from the Cirque deposit indicate reserves of 30 mi llion tonnes of baritic lead-zi nc-si lver ore. Similar bedded barite deposits are also reported from Midway area, near the Yukon border.

Jan 1, 1984

By T. Urbancic, Eric von Lunen, G. Viegas, A. Baig

"The characterization of the failure process of induced fractures by hydraulic stimulation is fundamental to understanding the generation and evolution of the discrete fracture network within the reservoir. A more detailed analysis of the fracture mechanism can be a powerful tool for identifying fluid flow paths and proppant placement within the reservoir. For example, during the rupture process the energy release is partitioned into different physical processes for which the relative ratio is changed by the presence of fluids or rotations in the local stress field with relation to the frictional resistance in the fracture plane. Fractures occurring in the same host rock under the same stress conditions are expected to rupture similarly, independent of their size (self-similarity). Changes in the scaling relationships of fractures are indicative of a change in the failure process, host rock or in-situ stress. Correlation of failure process data with reservoir rock properties and the in-situ stress field will help identify regions within the reservoir with characteristic types of failures. Further correlation with hydrocarbon production data can be used to develop efficient treatment plans and production diagnostic tools.In this study we investigate the failure process of ~27,000 microseismic (M < -1) fractures induced during a hydraulic fracturing shale completion program in NE British Columbia, Canada by estimating static and dynamic source parameters, such as dynamic and static stress drop, radiated energy, seismic efficiency, moment tensor, fracture plane orientation, slip direction and rupture velocity. On average, the microseismic events have low radiated energy, low dynamic stress and low seismic efficiency, consistent with the obtained slow rupture velocities. Events fail in overshoot mode (slip weakening failure model), with fluids lubricating faults and decreasing friction resistance. Events occurring in deeper formations tend to have faster rupture velocities and are more efficient in radiating energy. Variations in rupture velocity tend to correlate with variation in depth, fault azimuth and elapsed time, reflecting a dominance of the local stress field over other factors.Further identification of spatial and temporal distribution of families of events with similar characteristic rupture behaviors, based on either rock formation, depth, source type, fracture plane orientation, stress drop, pad or proppant stage, may be used as a proxy for specific fracture network development and hydrocarbon production. This information may be used to determine reservoir properties, constrain reservoir geo-mechanical models with measured physical parameters, classify dynamic rupture processes for fracture models and improve fracture treatment designs. These will be the focus of future studies."

Jan 1, 2015

By E. H. Rose

THE most useful guide to the role of lime in flotation is the view that the chemistry of any flotation operation is primarily a pattern in relative solubilities. We have the coming together of a number of minerals, reagents, fortuitous salts, water, and oxygen, many of which have not been previously in contact with each other, and every one of which is free, at least to some extent, to abandon old alliances and to form new ones. Of one thing the operator may be sure, and that is that, when equilibrium has been reached, those new chemical combinations will have formed which are the least soluble combinations possible to the environment. The laws of solution govern the operation, which means that relative concentrations are always a factor, and temperature frequently is. What the operator is really doing when he chooses his reagents .in the first place (empirically or otherwise) and works out their? optimum amounts, is to provide an environment in which (1) the least soluble possible compound of the mineral he desires to float is one which is also non-wettable, while at the same time (2) the least soluble compounds possible to the minerals he desires to depress are wettable. Since all metathesis is reversible, perfection is impossible to achieve, and the operator is constantly striving to establish that combination of concentrations which will drive each and every particular reaction as far as possible in the direction he desires it to go, in accordance with the law of molar concentration.

Jan 1, 1939

By Michael Loken, April Montera

"The process of blending consistent and predictable feed for the roasters is critical to optimizing product quality and controlling production costs. To assist in this process, Online PGNAA Slurry Analyzers have been installed and evaluated at a Sudbury Ontario smelter. They are used to measure 100% of the full process stream to obtain elemental composition data in real time. This paper explains the application details at Sudbury and the benefits achieved from their Full Stream, Elemental Slurry Analyzers.INTRODUCTIONSudbury Integrated Nickel Operations (Sudbury INO), a Glencore Company consists of two underground nickel/copper mines in Sudbury, Nickel Rim South and, Fraser, along with the Strathcona mill and the Sudbury smelter. The facilities are spread throughout the 60 kilometer-long, oval-shaped geological formation known as the Sudbury Basin (Figure 1). The company has been mining nickel-copper ores in the Sudbury area since 1929. Nickel and copper are the primary focus of operations at Nickel Rim South and Fraser. Other base metals such as cobalt and precious metals are also produced."

Jan 1, 2016

By Jerry Handford

Investing in the Development of our Future Workforce ?Collaborative partnerships with educational institutions, industry associations, governments and other businesses. ?Programs: »Co-op / Discipline Student Program »Trades Development Initiatives »Operator Training Programs »General Student Program »Careers Next Generation / Community Careers Co-operative

May 1, 2006

By M. G. Lipsett

One challenge in applying information technologies in Mining is building a business case. In Mine Maintenance, there is a complex flow of information that contributes to making informed business decisions. By understanding those information relationships and the cost of wrong decisions, analysts can estimate the value of information flow. Developers can then ensure that systems deliver key information in an accurate and timely way. In this paper, general maintenance decision-making is discussed, with examples of how model-based analysis can improve the information delivered to decision makers.

May 1, 2001

By H. J. Ni, M. Y. Huang, S. W. Chen

The effects of several fluxes on purification, microstructures and properties of A00 aluminium have been studied. The experimental results and analyses indicate that many cracks and large porosities exist in the surface film above the melt purified by C2Cl6 and that the film is floe and mostly composed of AhO3 and pure aluminum, which carries many carbon particles and AlCh not fully volatilized. And then over 50% of the all-melting residue is pure aluminum, which is one of the major reasons for high melting loss. Moreover, because of a mass of gas bubbles and a state of seethe, there exist many inclusions which size is under l0µm in the microstructure of A00 aluminum purified with C2Cl6 or fluxes containing C2Cl6- With this purifying method, the aluminum crystal grains are extended along the radius that was observed firstly and the average crystal size of A00 aluminum are about 100µm~150µm. In addition, small size inclusions have little affected on tensile strength and micro inclusions under l0µm have little affected on elongation.

Jan 1, 2006

By M. M. Papic, G. M. Kimber

"Hat Creek coal was treated by the liquid solvent extraction process in a continuous plant at the U.K. National Coal Board Coal Research Establishment.Extraction levels of over 80 per cent dry-mineral-matter-free (dmmf) coal were achieved.Total light oil yield was around 47 per cent of the dmmf coal. The light oil was shown to be a good feedstock for secondary refining into gasoline, jet fuel and diesel fuel.In spite of the high mineral matter content of the coal the solid residue was successfully removed from the coal extract by filtration.IntroductionBritish Columbia Hydro (BCH) and the National Coal Board of Great Britain (NCB) undertook a joint project to test the Hat Creek coal from British Columbia in the NCB&apos;s coal liquefaction process designed to produce transport fuels and feedstocks for the chemical industry by the liquid solvent extraction of coal(1), In this process most of the coal is dissolved in an aromatic solvent and the residual solids consisting of mineral matter and undissolved coal are removed by filtration. The resultant coal extract solution is fed to a hydrocracker for conversion to light liquid products and a fraction suitable for recycling as solvent. The light liquid products can be converted to gasoline and diesel fuel in a secondary refining stage.The dissolution of the coal is effected by heat-treating a slurry at a temperature in the region of 400°C which causes some bonds in the coal to rupture with the formation of radicals(2,3). These radicals are stabilized by hydrogen transfer from the hydroaromatic groups in the solvent, resulting in a reduction in the molecular weight of the coal. In the absence of donor groups the radicals combine to form an insoluble high molecular weight product(4). From studies of the kinetics of these reactions it has been shown that the formation and stabilization of the radicals is rapid at temperatures around 400°C(2,3). The dissolution of the depolymerizing coal is, however, relatively slow and the need to ensure complete dissolution in order to achieve a high extraction restricts the selection of digestion time(5). Further, it is important that digests do not contain depolymerizing coal as it may re-form under the applied stress in the filter cake inhibiting flow through the bed and resulting in low filtration rates(6).Thus, in practice relatively long digestion times are generally required in order to ensure complete dissolution of the depolymerizing coal, while it is also important to avoid depletion of the hydrogen donor groups in the solvent which would lower the rate of hydrogen donation to the coal and thus reduce the extraction yield and adversely affect the filtration(7). Clearly it is desirable to optimize the digestion time and temperature with regard to the extraction yield and filtration properties.The precise control of the distribution of products from the hydro-cracker is important for the composition of the recycle process solvent. The principal functions of the solvent are to provide a source of donatable hydrogen and a vehicle for the dissolution of the depolymerizing coal. Hydrogen transfer from the solvent, achieved by the conversion of hydroaromatic to aromatic groups, stabilizes the radicals formed by thermal cleavage of some of the bonds in the coal resulting in a progressive reduction in the size of the coal molecules(8,9) and dissolution in the solvent. The combination of radicals would result in the formation of insoluble material and a reduced extraction yield of the coal(4). Thus to achieve a high extraction yield the solvent should contain sufficient hydrogen donor groups to prevent extensive radical combination. The composition of the solvent should also be controlled to allow dissolution of the depolymerizing coal and to prevent precipitation of this material during the subsequent processing of the coal digest and extract solution. The formation of a precipitate not only reduces the extraction yield of the coal and adve"

Jan 1, 1985

By R. H. Duval

"In May 1936, Pamour started producing gold by cyanidation of flotation concentrates, and in 1939 was milling about 1, 600 tons per day.Refining records dating from 1939 show two oil-fired furnaces in use, (Rockwell type 46 11 x 29 11 inside oval shell).Refining time averaged 7. 83 hours during the year 1939, indicating a complete refining shift of about 9. 33 hours. That year appears to be characteristic of the period with regard to time required and results obtained.For that year total fineness (gold + silver) of the bars averaged 940 (approx.), but it frequently dropped below this figure, sometimes far below.Furnace lining life varied widely from three to seven or more months. Sillimanite was the standard lining but Mullfrax 41 was frequently used.For many years refining practice remained practically unchanged, and in 1960 procedure still consisted essentially of mixing a flux(% Composition Borax 41, Silica 11, Soda-Ash 11, Nitre 15, Mn02 22) with cyanidation precipitate in the ratio of l. 2 to l and heating to a medium heat (yellowishred, 2000° F) with a low flame for a long time. Time required was about 10. 5 hours per refining. Results were still much as detailed above.At this time it was decided to revise refining procedure, in an effort to shorten refining time and obtain consistently good bullion fineness."

Jan 1, 1965

By M. Leroux, S. R. Rao, J. A. Finch

"Poor Pb/Zn selectivity during Pb flotation in laboratory tests on a Mississippi Valley-type Pb/Zn ore was traced to a pH effect. In the pH range 9.5-11 sphalerite floated readily without copper activation. Compared to sphalerite flotation with copper activation this procedure gave equivalent selectivity but reduced flotation rate.Possible mechanisms of this sphalerite flotation without copper activation are discussed. Activation by Fe(OH) 2 is suggested, the Fe++ions being derived from superficial oxidation of pyrite in the ore.INTRODUCTIONGalena and sphalerite commonly occur together. The usual practice is to float galena first followed by the flotation of sphalerite after activation with copper (II) sulphate. If ores contain pyrite it is depressed by maintaining an alkaline pH (9- 10) and using NaCN as depressant.In flotation tests with a Pb/Zn ore from Polaris selective flotation of galena could not be achieved consistently as a considerable amount of sphalerite, even though unactivated, floated. A systematic study was carried out to determine the cause of this problem. This led to the unexpected finding that sphalerite floated in the alkaline pH range 9.5-11.0 without preactivation with Cuso 4 . This paper describes the results of this study and discusses a possible mechanism of the flotation of sphalerite."

Jan 1, 1987

?Bank Lending to the Mining Sector affected by 2 broad factors since Mid 2008: 1. Economic Downturn (?the Real Economy?) for mining companies directly reflected in lower metal prices (current and forecasted). In the case of gold companies, minimal effect. 2. Financial Crisis (?the Credit Crunch?) as it has affected the lending activities of those banks active in the mining sector.

May 1, 2009

By Euler M. De Souza

"This paper presents a study developed to assess the potential use of salt tailings as backfill to control surface subsidence and as a mine bulkhead used to isolate areas of potential brine inflows. A series of index tests, centrifuge model tests and quasi-static creep consolidation tests were performed to evaluate the creep and consolidation properties of salt backfl1l and to evaluate the effect of brine inflow and brine infiltration on backfill behaviour. The centrifuge models were specifically designed to study the mechanical behaviour of salt backfill under the influence of brine inflow and long-term creep. Test results indicated that salt tailings could be applied underground as a bulkhead to seal off areas of potential inflow with the additional advantage of controlling room closure and local back instability. It is hoped that this study will assist mine planners to develop contingency plans to control brine inflow occurrences. IntroductionThe use of salt tailings as backfill is a technique that would assist in the control of potential brine inflows and surface subsidence, and would have a very positive impact on the long term adverse environmental effects associated with surface salt tailings disposal. A centrifuge testing program was designed to evaluate the behaviour of salt tailings as backfill; the effectiveness of salt backfill as a bulkhead used to isolate areas of potential brine inflow and the potential use of salt backfill to control surface subsidence. The testing program was also used to evaluate the creep-consolidation properties of salt backfill and to evaluate the effect of brine inflow and brine infiltration on backfill behaviour. This paper presents the results of the experimental centrifuge testing program and a comparison of results with models tested under I g using an electrohydraulic servo-controlled loading frame (MTS) and a creep consolidation cell. Applicability of the results to practical underground soft rock mining is also discussed.The centrifuge model tests indicated that salt tailings could be applied underground as bulkheads to seal off areas of potential inflow with the additional advantage of controlling room closure and local back instability. Because the applied stresses (1.2 MPa) and fill consolidation were relatively low, the centrifuge simulated bulkhead did not retain all of the inflow brine. At typical field stresses it is expected that the fill would be able to seal off panels with brine inflows. Further testing at higher stresses are suggested to determine the consolidation and stress levels at which the fill would completely retain any potential brine inflow head and positively act as mine bulkhead."

Jan 1, 1994

By T. Saksala

In this paper, the embedded discontinuity approach is applied to finite element modeling of rock fracture. A rate-dependent constitutive model based on the embedded displacement discontinuity theory is developed to describe the mode I, mode II and mixed mode fracture of rock in tension and compression. The bulk material is described as linear elastic until reaching the elastic limit. Beyond this limit, a ratedependent exponential softening law governs the evolution of the embedded displacement jump. The present approach incorporates the rock heterogeneity by random description of the mineral texture of rock. Moreover, the inherent initial microcrack populations of natural rocks are accounted for as randomly oriented embedded discontinuities. Numerical examples demonstrate the model behavior in uniaxial compression and tension. The effect of loading rate and confining pressure is tested as well in 2D numerical simulations. These simulations show that the model captures the main features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it has an important advantage of accounting for the orientation of introduced microcracks.

Jan 1, 2015

By U. Troncoso

Mantoverde is a heap leach-SX-EW operation that was commissioned in December 1995 at a production rate of 42,130 ton of copper per year and 5.4 million ton of ore per year. Copper production has been steadily increased to reach 62,000 ton in 2005. The forecast copper production for 2006 is 60,300 ton for an ore treatment rate of 9.5 million ton. A first dump leach operation was started in 1999 at a production rate of 1,922 ton of copper. A second dump leach operation was started in early 2002 at a production rate of 2,805 ton of copper. Dump leach production will be increased over time to as much as 24,000 ton of copper. Several improvements in the heap leach process have been implemented to cope with the higher ore throughput and copper production. However, the solvent extraction plant has remained unchanged which has resulted in a lower availability of raffinate solution and, as a consequence, in longer leach cycles. Different studies have been undertaken in order to optimize the solution management system at Mantoverde, including column test work aimed to reduce the leach cycle and solvent extraction plant modifications aimed to increase the raffinate solution availability. The test work program and the economical evaluations carried out, as well as the conclusions and recommendations obtained, are discussed in this paper.

Jan 1, 2007

By G. A. Sutton

This paper, describes a case example from San Manuel mine, where in situ copper leaching of the supergene zone was done over a 14 year period (1986–1999) in conjunction with underground and open-pit mining operations of a copper porphyry deposit. In 1993–1994, testing of well fields was done to determine the amount of copper that would be recovered from in situ leaching of the supergene zone, which was composed primarily of chrysocolla and copper-clay minerals. It was determined that the leach fluid would reach 70% (‘sweep efficiency’) of the copper minerals and that 75% of them would be leached for a recovery of 52% of the acid soluble copper. However, the final results from Zone 6, which had the longest leach history, showed that approximately 42% of the acid soluble copper was recovered, indicating that the `sweep efficiency’ was closer to 55%. Comparison of drill-core assay data from two holes, one drilled before (ARM158) and the other after (SMO9607) leaching, also indicate that approximately 42% of the acid soluble copper was recovered. The discrepancy between the predicted (52%) and actual (42%) recovery is probably related to a combination of factors, including difficulty in maintaining fluid saturation, channeling effects and gypsum precipitation. INTRODUCTION In situ copper leaching at the San Manuel mine, Arizona, was initiated in 1986. It was recognized that some of the copper oxide resource was not going to be economically recoverable by conventional open pit and heap leach methods using solvent extraction and electrowinning (SXEW). A high stripping ratio would be required to access part of the resource. At the time, in situ leaching was becoming popular in the uranium industry but the approach was virtually unknown in the copper industry, especially not at a large scale.

Jan 1, 2019

By Anthony J. Deevy

"The Magino gold mine is located 45 km northeast of Wawa, Ontario. There was limited gold production in the late thirties. The present operation was officially opened in October 1988 and produced gold until September 1992. It was a 635 tonnes per day, decline-accessed mine, with ore coming from several small blast hole and shrinkage stopes.The host for the gold is the Webb Lake granodiorite stock which was intruded into the Goudreau Lake Deformation Zone. This east-northeast-striking deformation zone overprints the generally east-west- striking isoclinally folded metavolcanic and metasedimentary rocks, which make up the east end of the Michipicoten greenstone belt. The ore-shoots are controlled by dextral delatancy associated with the Goudreau Lake Deformation Zone. Shearing, bleaching and silicification accompanied the gold emplacement. IntroductionThe following is a general information paper on the Magino gold mine which is located 45 km- northeast of Wawa toward the east end of the Michipicoten greenstone belt. This paper summarizes the discovery, exploration and development history of the deposit. The geological characteristics are described, including regional geological setting, local mine geology, mineralization, alteration and structural history. The mining methods and the contribution of the geological staff to the successful development and mining of the gold deposit are also mentioned."

Jan 1, 1994

By Bennett McLaughlin

The Penna Shaft is the deepest single?lift shaft in North America. AGNICO-EAGLE started sinking the Penna shaft in 1995 with a hoisting plant capable of hoisting 1 800 tonnes per day from a 2 240-metre deep shaft. Exploration success at depth lead to the replacement of the existing double drum hoist by another double drum hoist capable of hoisting 7 000 tonnes per day. The use of another double drum hoist, instead of a Blair Multi-Rope winder, to hoist 24,5-tonne skips was only made possible by lowering the safety factor. This paper describes recent experiences at Penna and in South Africa, and examines the possibility of extending the double drum hoisting system to a depth of three kilometres.

May 1, 2003

By A. Pranowo, G. R. F. Alvear F., N. Aslin, M. S. Moats

"The toxicity of arsenic is well known and documented; however, the presence of arsenic in copper electrorefining anodes and electrolytes is critically necessary to produce high-quality cathode. Arsenic as well as antimony and bismuth concentrations vary relative to their concentration in the anode copper received from the smelter. The behaviour and benefits of arsenic in copper electrorefining and the detrimental effects of antimony and bismuth on cathode quality and tankhouse performance are discussed. This will include the minimization and mitigation of problems associated with arsenic, antimony, and bismuth—including cathode contamination, floating slimes, scaling, and anode passivation.RÉSUMÉ La toxicité de l’arsenic est bien connue et documentée; toutefois, la présence d’arsenic dans les anodes de l’électroaffinage du cuivre et dans les électrolytes est d’une nécessité critique pour produire une cathode de grande qualité. Les concentrations en arsenic, ainsi qu’en antimoine et en bismuth varient selon leur concentration dans l’anode de cuivre reçue de la fonderie. Le comportement et les avantages de l’arsenic dans l’électroaffinage du cuivre et les effets indésirables de l’antimoine et du bismuth sur la qualité de la cathode et le rendement des cuves d’électrolyse sont discutés. On traite aussi de la minimisation et de l’atténuation des problèmes associés à l’arsenic, l’antimoine et le bismuth – incluant la contamination de la cathode, les schlamms flottants, l’entartage et la passivation de l’anode."

Jan 1, 2016

By James A. Finch, Yue Hua Tan, Wei Zhang

"The paper is part of our study of the frother structure-property relationship using bubble rise velocity. Single bubble rise velocity profiles were determined in a 350 cm column for surfactants from the polypropylene glycol (PPG) family. Using velocity at 300 cm, the concentration to reach minimum velocity (CMV) is determined. The CMV is shown to decrease as alkyl chain length (n, number of carbons) increases and as the number of propylene oxide groups (m) increases. Linear correlations log CMV vs. n and m were observed. Taking literature data for critical coalescence concentration (CCC), linear log CMV vs. log CCC correlations were also noted. Mechanisms are briefly discussed, and prediction of CCC made for a commercial polypropylene glycol.INTRODUCTIONAs one of the great enabling technologies of the 20th century, froth flotation is a highly versatile method for physically separating minerals by exploiting differences in wettability (hydrophobicity). Over the last century, flotation reagents have undergone significant developments (Khoshdast and Sam, 2011). One important group of reagents is frothers which are used to reduce bubble size, slow bubble rise velocity and help stabilize froth (Klimpel and Isherwood, 1991).Frothers, originally derived from natural sources (e.g., pine oil and cresylic acid), are largely replaced today by synthetic products which provide more consistent properties. Polyglycols, based on PEO (polyethylene oxide), PPO (polypropylene oxide), or PBO (polybutylene oxide) groups, were first described by Leja and Nixon (1957) and have attracted wide use since then (Farrokhpay 2011). The chemical structure of polyglycols can be represented by a general formula: R(X)mOH, where R = H, or CnH2n+1 and X stands for EO (-C2H4O-), PO (-C3H6O-), or BO (-C4H8O-). The polypropylene glycol ethers (CnH2n+1(PO)mOH) are the most common of these reagents (Pugh, 2007) and the focus of this study.In general, the chemical structure of frother molecules comprises two parts, a non-polar hydrophobic hydrocarbon (alkyl: CnH2n+1) chain and a polar hydrophilic head. By introducing the ether -Olinkage, which acts as another polar site, the propoxy group (-OC3H6-) in the structure makes the frother readily soluble in water (Somasundaran and Wang, 2006), facilitating the industrial use of these frothers. Available as by-products, Dow Chemicals introduced as series of polyglycols, e.g., Dowfroth (DF) 200, 250, 263, and 1012, the most familiar being DF250 (CH3(PO)4OH), a polypropylene glycol methyl ether. While no longer available from Dow, these and other polyglycols are still widely used."

Jan 1, 2016

By X. Zhong

Thermal shock resistant properties of reaction sintered bauxite-based ß -Sialon bonded corundum have been investigated, and the results are compared with those of Al2O3 based counterpart. It is found they all have very good thermal shock resistance. Their residual strength ratios after one thermal shock cycle at ? T=1200°C and A T=1350°C are 61-73% and 53-65% respectively. TSR parameters are calculated based on thermal expansion, modulus of elasticity, and fracture toughness determined. The reasons for improved TSR of these composite materials are discussed.

Jan 1, 2004