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Mineralogical Characterization of Sieved and Un-Sieved Samples

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Journal of Minerals and Materials Characterization and Engineering 2014年第1期2卷 40-48页

作者： Rolando Lastra William Petruk NRCan-canmet mining Ottawa Canada

Mineralogical characterization applied to mineral processing is now widespread. The first step for a mineralogi- cal characterization study is usually size fractionation. Preparation of polished sections is done on size fractions to reduce complications in making representative cross sections of particles with large size differences. A sample is commonly fractionated into five or six size intervals. The drawback of this procedure is that it makes liberation studies more expensive, because one sample actually produces five or six sub-samples that need to be studied, i.e. one from each size interval. Thus to reduce cost of liberation studies, it would be desirable to study the un-sized sample. This paper provides a comparative liberation study of a set of samples both using size fractions and using the un-sized samples. The samples studied are the feed, the concentrate and the tails of a lead rougher flotation circuit. The results consistently show significant differences between the sized and the un-sized samples. Nevertheless, the results indicate that un-corrected liberation data from un-sized samples can be used for comparative studies that involve several related samples. Thus, it is possible to improve (or further understand) a concentrator circuit by using mineralogical data from un-sized samples around such circuit.

关键词： Mineral Liberation Sieved Un-Sieved

Grain Size Distribution and Interfacial Heat Transfer Coefficient during Solidification of Magnesium Alloys Using High Pressure Die Casting Process

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Journal of Materials Science & Technology 2018年第2期34卷 324-334页

作者： P. Sharifi J. Jamali K. Sadayappan J.T. Wood Western University London Ontario Canada canmet MATERIALS Hamilton ON Canada

The objective of this study is to predict grain size and heat transfer coefficient at the metal-die interface during high pressure die casting process and solidification of the magnesium alloy AM60. Multiple runs of the commercial casting simulation package, ProCASTTM, were used to model the mold filling and solidification events employing a range of interfacial heat transfer coefficient values. The simulation results were used to estimate the centerline cooling curve at various locations through the casting. The centerline cooling curves, together with the die temperature and the thermodynamic properties of the alloy, were then used as inputs to compute the solution to the Stefan problem of a moving phase boundary, thereby providing the through-thickness cooling curves at each chosen location of the casting, Finally, the local cooling rate was used to calculate the resulting grain size via previously established relationships. The effects of die temperature, filling time and heat transfer coefficient on the grain structure in skin region and core region were quantitatively characterized. It was observed that the grain size of skin region strongly depends on above three factors whereas the grain size of core region shows dependence on the interracial heat transfer coefficient and thickness of the samples. The grain size distribution from surface to center was estimated from the relationship between grain size and the predicted cooling rate. The prediction of grain size matches well with experimental results. A comparison of the predicted and experimentally determined grain size profiles enables the determination of the apparent interracial heat transfer coefficient for different locations.

关键词： High pressure die casting Grain size lnterfacial heat transfer coefficient Solidification of magnesium alloys Process parameters

Mixed graphite cast iron for automotive exhaust component applications

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China Foundry 2017年第6期14卷 519-524页

作者： De-lin Li canmet MATERIALS Natural Resources CanadaHamiltonONCanada

Both spheroidal graphite iron and compacted graphite iron are used in the automotive industry. A recently proposed mixed graphite iron exhibits a microstructure between the conventional spheroidal graphite iron and compacted graphite iron. Evaluation results clearly indicate the suitability and benefits of mixed graphite iron for exhaust component applications with respect to casting, machining, mechanical, thermophysical, oxidation, and thermal fatigue properties. A new ASTM standard specification(A1095) has been created for compacted, mixed, and spheroidal graphite silicon-molybdenum iron castings. This paper attempts to outline the latest progress in mixed graphite iron published.

关键词： SiMo iron spheroidal graphite compacted graphite mixed graphite exhaust components brittleness at medium temperature thermal fatigue cycles

Microstructure,texture and mechanical behavior characterization of hot forged cast ZK60 magnesium alloy

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Journal of Materials Science & Technology 2017年第9期33卷 907-918页

作者： S.M.H.Karparvarfard S.K.Shaha S.B.Behravesh H.Jahed B.W.Williams Department of Mechanical & Mechatronics Engineering University of Waterloo canmet MATERIALS Natural Resources Canada

structure with a significant reduction in casting porosity, while the texture changed to sharp basaMeasured mechanical properties of the forged alloy showed that strength did not change, howductility improved by 75%. The analysis of the fracture surface of the forged alloy under tension rea ductile fracture with dimple morphology, while the as-cast alloy displayed a brittle fracture with pores. This demonstrated that the reduction of casting defects and dendritic morphology, as well evolution of recrystallized grains, enhanced ductility, while partial dynamic recrystallization throuforging process resulted in only marginal modification of strength in the forged condition.. 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials SciTechno

关键词： Magnesium Forging Ductility Texture Recrystallization

Effects of Collectors and Frothers on Copper and Molybdenum Coarse Particle Recoveries—A Statistical Approach

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Journal of Minerals and Materials Characterization and Engineering 2019年第3期7卷 117-136页

作者： Tony Di Feo Rolando Lastra Natural Resources Canada Canmet Mining Ottawa Canada

Typically, coarse dense mineral particles greater than 150 μm are difficult to float, and the recovery decreases progressively. Various physical parameters can be manipulated in an attempt to increase the recovery. These physical parameters are the following: liberation, turbulence in the flotation cell, pH, collector, frother type and dosage. The testwork discussed in this paper was performed for a copper-molybdenum operation that is experiencing coarse particle (>150 μm) losses in the tails. This operation uses Diesel No. 2 fuel and sodium ethyl xanthate for molybdenum and copper flotation, respectively and X-133 frother. In an attempt to increase coarse particle recovery, stronger collectors (potassium amyl xanthate, Aero 249 and Aero 3501) and frothers (FrothPro 618, FrothPro 630 and FrothPro 706) were used. The analysis was performed using the Analysis of Variance (ANOVA) approach. The conditions required by the ANOVA method were met. The results showed that the collector potassium amyl xanthate (PAX) with frothers X-133 and FrothPro 630 resulted in approximately 3% increase in copper rougher recovery relative to the baseline (sodium ethyl xanthate and X-133). The collectors and frothers did not have a significant effect on molybdenum recovery within the dosage limits investigated.

关键词： Mineral Particles Physical Parameters Coarse Particles Flotation

Attenuation of aqueous metal transport at two natural acid rock drainage occurrences in the Yukon Territory, Canada

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Chinese Journal Of Geochemistry 2006年第B08期25卷 229-230页

作者： Y.T. John Kwong canmet mining and Mineral Sciences Laboratories Ottawa Canada

EFFECT OF RARE EARTH ADDITIONS ON FRACTURE PROPERTIES OF 2.25Cr-1Mo STEELS

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Acta Metallurgica Sinica(English Letters) 1989年第1期2卷 63-68页

作者： W.R.TYSON B.FAUCHER Physical Metallurgy Research Laboratories CANMETOttawaCanada

The inclusion parameters,fracture surface morphology and void growth characteristics of ten- sile and fracture toughness specimens of 2.25Cr-1Mo steels with and without rare-earth (RE)additions have been investigated by quantitative metaltography(QTM),scanning elec- tron microscopy(SEM)and energy dispersive spectroscopy(EDS).There is a substantially higher density of inclusions in the RE-treated steel,which has lower values of fracture proper- ties including critical values of COD and J integral(δ_c and J_(IC)),fracture strain(ε_f) and Charpy V-notch energy(CVN).The fracture surface of the RE-treated steel comprises equiaxed dimples of diameters comparable with its inclusion spacing,whereas for the non-RE-treated steels,a wide range of dimple sizes is found with average diameter much smaller than the corresponding inclusion *** investigation indicates that the lower values of fracture properties for the steel with RE at room temperature may be ascribed to its large content of RE-containing inclusions.

关键词： Cr-Mo steel fracture properties inclusion parameters fracture morphology

热机械加工对Ti-V-N钢显微组织和机械性能的影响

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钢铁钒钛 1991年第1期12卷 81-93页

作者： Dogan B.Collins L.E.Boyd J.D. 王苹加拿大渥太华canmet

根据用凸轮式塑性计和淬火-变形膨胀仪分别对一种Ti-V微合金钢的奥氏体变形行为和连续冷却转变行为所做的研究,设计了钢板轧制程序,以得到:(ⅰ)再结晶奥氏体,(ⅱ)未再结晶奥氏体,(ⅲ)变形铁素体+未再结晶奥氏体。研究了奥氏体状态和冷... 详细信息

根据用凸轮式塑性计和淬火-变形膨胀仪分别对一种Ti-V微合金钢的奥氏体变形行为和连续冷却转变行为所做的研究,设计了钢板轧制程序,以得到:(ⅰ)再结晶奥氏体,(ⅱ)未再结晶奥氏体,(ⅲ)变形铁素体+未再结晶奥氏体。研究了奥氏体状态和冷却速度对最终显微组织和机械性能的影响。为了从理论上解释最终铁素体晶粒尺寸随不同热机械加工工艺制度的变化,除了要考虑铁素体成核点的密度外,还必须考虑铁素体晶粒长大动力学,说明了膨胀仪研究在确定某一钢最佳变形工艺制度和冷却速度方面的好处。拉伸和冲击性能的范围宽,是由于所研究的显微组织不同造成的。屈服强度随变形铁素体、贝氏体或马氏体量的增多而提高,随铁素体晶粒尺寸的减小而提高,冲击韧性受铁素体晶粒尺寸和轧制平面出现分层的影响最为强烈。

关键词：热机械加工显微组织机械性能

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超细晶钒微合金化双相钢性能

钢铁钒钛 2017年第4期38卷 94-104页

作者： C.P.Scott F.Fazeli B.Shalchi I.Pushkareva 杨雄飞 canmet Materials Natural Resources Canada

研究了钒微合金化对高强双相钢微观组织及性能的影响。与Fe-0.186C-1.5Mn-0.3Si-0.008N参照钢相比,加入0.14%V带来如下效果:(1)在冷轧及退火状态铁素体晶粒高度细化;(2)严重推迟在连续退火过程中铁素体向奥氏体转变的初始动力学;(3)慢... 详细信息

研究了钒微合金化对高强双相钢微观组织及性能的影响。与Fe-0.186C-1.5Mn-0.3Si-0.008N参照钢相比,加入0.14%V带来如下效果:(1)在冷轧及退火状态铁素体晶粒高度细化;(2)严重推迟在连续退火过程中铁素体向奥氏体转变的初始动力学;(3)慢冷条件下铁素体开始转变温度稍微提高,但珠光体和贝氏体转变被抑制,导致淬透性提高;(4)在临界退火温度≤740℃时观察到未溶渗碳体;(5)750℃/180 s退火后铁素体相中发现大量V(C,N)析出(平均直径7.4 nm),而马氏体(奥氏体)中析出物稀少,尺寸更大(平均直径13.4 nm);(6)不含钒参照钢抗拉强度随马氏体体积分数增量为~16 MPa/%,而含钒钢由于晶粒细化和铁素体选择强化,强度随马氏体含量变化增量相当低(~4 MPa/%),在马氏体体积分数>45%变软。

关键词： DP钢 AHSS 超细晶钒微合金化