Oxygen isotope exchange between refractory inclusion in Allende and solar nebula gas

A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope composition (approximately 5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). Some of the melilite is also anomalously enriched in oxygen-16 compared with oxygen isotopes measured in other CAIs. The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope exchange with the surrounding oxygen-16-poor nebular gas progressed through the crystallization of the CAI. Additional oxygen isotope exchange also occurred during subsequent reheating events in the solar nebula.     

16O excesses in olivine inclusions in Yamato-86009 and Murchison chondrites and their relation to CAIs

In situ ion microprobe analyses of oxygen isotopes in Yamato-86009 and Murchison chondrites show that they contain abundant olivine-rich inclusions that have large oxygen-16 (16O) excesses, similar to those in spinel grains in calcium-aluminium-rich inclusions in Allende and other carbonaceous chondrites. The existence of 16O-enriched olivine-rich inclusions suggests that oxygen isotopic anomalies were more extensive in the early solar system than was previously thought and that their origin may be attributed to a nebular chemical process rather than to an unidentified 16O-rich carrier of presolar origin.     

金牙金矿地质特征及金的赋存状态研究

对金牙金矿床的主要地质特征作了较为详细的描述．对矿区氧化带进行了划分，并对金牙金矿矿石中金的分布及其赋存状态作了研究．结果表明，金的赋存形式主要有三种：即显微—超显微自然金包体形式、类质同像固溶体形式以及肢体吸附形式．在原生矿石中，载金矿物主要为毒砂，次为黄铁矿；在氧化矿石中，主要为粘土类矿物，碳质及褐铁矿等．     

次氯酸钠高碱高盐氧化分解贵州某难处理金矿载金硫化矿的研究

在我国南方广泛发育着产在富亩有机质的海相细粒碳酸盐型沉积碎屑岩系的碳质难处理金矿在这类金矿中金以微细粒自然金赋存在黄铁矿等载金矿物中,常规氰化难以浸出,浸出率大约为10% 。去除载金硫化矿物的包裹干扰是实现金浸出的有力措施．次氯酸钠作为一种强氧化剂特别适台碳酸盐岩矿浆舟质中氧化分解硫化矿去除金浸出的包裹干扰。黄铁矿的氧化分解受有效氯浓度、氯化钠浓度、液固比及pH等多种因素的干扰,经次氯酸钠氧化分解后,金的包裹干扰已基本消除,金的浸出率可达85%     

碳质金矿的矿物特征和提金工艺

论述了碳质难处理金矿中碳质物的组成和矿物特性,碳质金矿预处理工艺和提金方法,并重点评述了水氯化法预处理和次氯酸盐浸出我国某些碳质金矿的试验研究结果。     

The clustering of alumina inclusions

Factors influencing the tendency of alumina particles in steel to agglomerate and form large clusters during deoxidation and solidification have been investigated by deoxidizing melts of Fe-10 pct Ni alloys with 0.1 pct aluminum under an inert atmosphere. Clusters of alumina inclusions are formed when the melt is stirred by either inductive or mechanical means. Nearly all of the inclusions are found in the clusters if the stirring time is long enough or at moderate stirring rates. Inclusions within the clusters increase in size with time while the size of inclusions in nonclustered regions remains essentially constant. The oxygen content of an ingot solidified soon after deoxidation corresponds well with that calculated from the oxygen content of the charged materials. After most inclusions have migrated to the clusters, the oxygen content in nonclustered regions is found to be as low as 2 ppm. Formerly Graduate Student, M.I.T..     

总氧含量对齿轮钢中非金属夹杂物的影响

为了保证齿轮钢中非金属夹杂物的控制,并确定齿轮钢经济合理的总氧含量控制目标,开展了总氧含量对齿轮钢中非金属夹杂物的影响研究。以三种不同总氧含量的Mn–Cr系齿轮钢为研究对象,利用Aspex扫描电镜、极值法、疲劳测试等不同方法研究了齿轮钢中非金属夹杂物数量、分布、尺寸等,获得了夹杂物与齿轮钢总氧含量的对应关系。在本文实验条件下,随着总氧含量的降低,钢中氧化物夹杂数量不断减小,其中5～10 μm的小尺寸夹杂物减小最明显,而10 μm以上的大尺寸夹杂物数量变化规律不明显。另外,极值法和疲劳试验结果表明,总氧含量高时（质量分数为0.0013%）,钢中最大氧化物夹杂尺寸也较大,比总氧质量分数为0.0010%和0.0005%的实验钢的最大夹杂物尺寸高10 μm以上,且当总氧含量比较低时（质量分数≤0.0010%）,实验钢总氧质量分数变化（0.0010%、0.0005%）对钢中最大夹杂物尺寸影响不大。      

甘肃洛坝铅锌矿选矿流程考察与优化

我国铅锌矿产资源丰富,但其自然禀赋差且矿物组成复杂,导致其综合回收利用难度大。甘肃洛坝铅锌矿是一座含铅锌且伴生有少量银、硫的泥岩—细碎屑岩型铅锌矿床,因其矿石性质复杂,较早期形成的矿石性质发生明显变化,导致铅锌分选指标及精矿质量下降。为解决现有选矿生产过程中存在的问题,寻找适宜的改进措施和方法,以提高铅锌资源综合利用效率,在研究矿石性质的基础上开展了详细的工艺流程考察。研究结果表明：矿石中碳质、硅质等脉石矿物含量升高,碎磨过程易于泥化,且吸附性能和可浮性好,这些是影响铅锌分选指标的主要因素;通过优化碎磨工艺参数,减少了碳质、硅质等脉石矿物的泥化程度;在浮选工艺中添加适宜抑制剂,并采用高选择性的铅、锌矿物捕收剂,可显著提高铅、锌精矿品位和质量,大幅提高铅、锌回收率,从而实现该复杂含碳低品位铅锌资源的高效综合回收,并为同类矿产资源的选矿回收提供参考依据。     

碳质金矿中碳质物的物质组成及其与金的相互作用

本文利用广西风山县金牙金矿对碳质金矿中的碳质物进行了研究。探索出从矿石中有效分离各种碳质组分的方法。在碳质物中发现如下的三种物质：（１）活性炭类物质（２）腐殖酸（３）长链酯或长链酯与长链烷烃的混合物。进一步的实验结果表明：产生“劫金”作用的碳质物主要为活性炭类物质,腐殖酸次之,酯或烃类似乎与劫金效应无关。但总的来讲,金牙金矿中碳质物的劫金作用较弱,金滩浸的主要原因不是碳质物对金的吸附,而强能是金的     

Assessment of Oxygen Control and Its Effect on Inclusion Characteristics during Electroslag Remelting of Die Steel

Deoxidation during electroslag remelting of S136 die steel was experimentally studied. The characteristics of inclusions in the electrode and ESR ingots were determined by image analyzer and SEM‐EDS. The results show that the oxygen content can be reduced from 89 ppm in the electrode to the lowest (12 ppm) in the ingot only when protective Ar gas remelting in combination with specially designed slag deoxidation treatment were employed simultaneously. The proportion of the oxygen combined as oxide inclusions increases with decreasing the total oxygen content in ESR ingot. The original inclusions in the electrode are mainly large (Mn,Cr)S and the large inclusions in the form of Al₂O₃ core surrounded by an outer sulfide layer, besides a few pure Al₂O₃ inclusions. After ESR process, while only pure Al₂O₃ inclusions with the size of about 1 µm were observed in ESR ingots. The large inclusions in the electrode were removed during ESR process. With higher oxygen content in the ingot, the contents of inclusions and large inclusions would be relatively higher. The results from industrial experiments have confirmed the availability of the present oxygen control technique. The mechanisms of oxygen behavior and control as well as inclusion evolution during ESR process were proposed based on experimental results along with thermodynamic analysis.     

Effect of electromagnetic stirring on inclusions in 304 stainless steel electroslag ingot

Based the self designed electroslag remelting furnace with electromagnetic stirring, the effect of external magnetic field on the number, size and type of inclusions in 304 stainless steel electroslag ingot was analyzed in detail. The content of oxygen and nitrogen in electroslag ingot was analyzed by ONH analyzer, and the morphology and element distribution of inclusions were observed by SEM. Finally, the ASPEX was used to analyse the size, number and type of inclusions. The results show that the oxygen content in electroslag ingot increases from 23.7×10-6 in consumable electrode to 64.70×10-6 whether magnetic field is applied or not, and the oxygen content increases to 67.4×10-6 at most from 23.7×10-6 in the electrode. But the nitrogen content in electroslag ingot decreased slightly to 659.3×10-6 from 675.5×10-6 in the electrode. The magnetic field has almost no effect on the type of inclusions, which mainly includes Al2O3, MnS-Al2O3, Al-Si-O, Al-Ca-O, Al-Si-Ca-O, Al-Mg-O and other inclusions. After the magnetic field is applied, the amount of large inclusions in electroslag ingot decreases, but the total number of inclusions increases when the magnetic induction intensity is small. When the magnetic induction intensity is 10 mT, the number of inclusions increases by 42.60%, but the maximum size of the inclusions decreases.     

电磁搅拌对304不锈钢电渣锭夹杂物的影响

摘要：通过自行设计的带电磁搅拌的电渣重熔炉,以304奥氏体不锈钢为研究对象,详细分析外加磁场对电渣锭夹杂物数量、大小以及类型的影响。采用氧氮氢分析仪检测氧、氮气体含量,采用扫描电镜观察夹杂物的形貌、组成,并采用ASPEX分析夹杂物的尺寸变化。结果表明,无论是否外加磁场,电渣锭中的氧含量都有所增加,从自耗电极中氧质量分数由23.7×10-6最高增至64.70×10-6;而相比于自耗电极,氮含量略微降低,其质量分数从675.5×10-6降低至659.33×10-6;无论是否加入磁场,电渣锭中的夹杂物种类并无变化,主要由Al2O3、MnS-Al2O3、Al-Si-O、Al-Ca-O、Al-Si-Ca-O、Al-Mg-O及其他夹杂物组成;在施加磁场后,电渣锭中的大颗粒夹杂物数量有所减少。外加磁场强度较小时并不能有效去除夹杂物,反而会增加夹杂物的数量,当磁感应强度为10mT时,夹杂物数量相比于未加磁场时增加了4260%,但是最大尺寸有所减小。     

Cleanliness of Alloying Structural Steel

 Alloying structural steel used for mechanical structures has a high requirement for cleanliness because its failures are greatly affected by non-metallic inclusions and total oxygen content in steel. It has been reported by some steelmaking plants to have some problems in controlling total oxygen content and inclusions during alloying structural steel production. For this purpose, cleanliness control in 02C-03Si-06Mn-1Cr-02Mo steel was investigated. Firstly, low melting temperature zone (≤1873 K) of CaO-Al2O3-MgO system and formation condition of low melting temperature inclusions were investigated through thermodynamic equilibrium calculation. On this basis, industrial tests were carried out. Through sampling at different stages, transformation of oxide inclusions and change of total oxygen content in steel were studied. The results show that: in order to form CaO-Al2O3-MgO system inclusions with low melting temperature, mass percent of Al2O3, MgO and CaO in inclusions should be controlled from 376% to 708%, 0 to 174% and 255% to 606%; For the condition of 1873 K and 005% (mass percent) dissolved aluminum in steel, the activities of dissolved oxygen, magnesium and calcium should be controlled as 0298×10-4-2×10-4, 01×10-5-40×10-5 and 08×10-8-180×10-8 respectively. With secondary refining proceeding, average total oxygen content and inclusion amount decrease, the type of most inclusions changes from Al2O3 after tapping to Al2O3-MgO after top slag is formed during ladle furnace refining and finally to CaO-Al2O3-MgO after RH treatment. In the final products, average total oxygen content was 127×10-6 and most inclusions were in spherical shape with size less than 5 μm.     

高碱度精炼渣对GCr15轴承钢洁净度的影响

 利用实验室渣-钢平衡试验研究了高碱度精炼渣对GCr15轴承钢中[w(T[O])]和夹杂物的影响。结合试验结果和热力学分析,探讨了钢中[w(T[O])、]夹杂物尺寸分布和粒径大小的变化规律,以及氧化物夹杂的转变过程。研究结果表明,碱度为6时,精炼渣(59.4%CaO-24.8%Al2O3-9.8%SiO2-6%MgO)可将钢中[w(T[O])]控制在0.000 6%以内,氧化物夹杂平均尺寸最小为2.26 μm。随着钢中[w([Ca])]和[w([Mg])]的增加,钢中氧化物夹杂转变过程为Al2O3→MgO·Al2O3→MgO→CaO-Al2O3-MgO复合夹杂物(核心为MgO,外围包裹着CaO-Al2O3)。渣-钢反应前期钢中以MgO·Al2O3为主,后期以MgO和CaO-Al2O3-MgO复合夹杂物为主。氧化物夹杂转变的试验结果与热力学分析结果相一致,大多数氧化物夹杂尺寸小于5 μm。     

常见的难熔包体矿物学特征分析

对地质矿物中的尖晶石-富钙辉石难熔包体进行了矿物化学研究,包体近似球形,边部为斜长石和橄榄石层。包体中残留颗粒较小的铁镍金属,包体外部形态不是由气-固凝聚形成,大多数情况下是由于熔融结晶形成,本文结合前人对难熔包体的研究,更清晰的描述了不同类型难熔包体的特征,我们按照富钙-铝包体中的主体矿物或矿物颗粒的大小来对难熔包体类别进行区分,有助于对难熔包体的分类进行深入研究。     

Effect of Mg Addition on the Refinement and Homogenized Distribution of Inclusions in Steel with Different Al Contents

To investigate the effect of Mg addition on the refinement and homogenized distribution of inclusions, deoxidized experiments with different amounts of aluminum and magnesium addition were carried out at 1873 K (1600 °C) under the condition of no fluid flow. The size distribution of three-dimensional inclusions obtained by applying the modified Schwartz–Saltykov transformation from the observed planar size distribution, and degree of homogeneity in inclusion dispersion quantified by measuring the inter-surface distance of inclusions, were studied as a function of the amount of Mg addition and holding time. The nucleation and growth of inclusions based on homogeneous nucleation theory and Ostwald ripening were discussed with the consideration of supersaturation degree and interfacial energy between molten steel and inclusions. The average attractive force acted on inclusions in experimental steels was estimated according to Paunov’s theory. The results showed that in addition to increasing the Mg addition, increasing the oxygen activity at an early stage of deoxidation and lowering the dissolved oxygen content are conductive to the increase of nucleation rate as well as to the refinement of inclusions Moreover, it was found that the degree of homogeneity in inclusion dispersion decreases with an increase of the attractive force acted on inclusions, which is largely dependent on the inclusion composition and volume fraction of inclusions.     

无取向电工钢WG350生产过程中夹杂物的行为与控制

为了更好地控制WG350无取向电工钢中的夹杂物,采用扫描电子显微镜、Aspex系统分析了精炼、连铸过程和成品板中夹杂物的类型、数量及尺寸的演变规律.结果 表明,氩站开始出现大尺寸含P复合夹杂物,该类型夹杂物大部分在RH脱碳后会上浮去除.RH加铝脱氧时生成的Al2O.以团簇状和块状为主,前者尺寸范围为0.5～5μm且大部...     

增氮析氮法生成气泡去除钢液中显微非金属夹杂物

为了进一步完善增氮析氮法生成气泡去除钢液中显微非金属夹杂物技术,研究了真空处理时间、充氮压力、气体类型等因素对钢中全氧和显微非金属夹杂物的影响.结果表明:减压处理过程中,钢液中非金属夹杂物可为过饱和气体氮气形成气泡提供非均相形核核心;增氮析氮法可有效地降低钢中全氧,去除钢中显微非金属夹杂物;真空处理时间越长,钢中全氧和显微非金属夹杂物数量越低,当真空处理时间为30 min时钢中全氧去除率达到了81.6%,而且全氧质量分数最低达到7×10-6.      

多孔炭质喷头在二次精炼中的应用

通过浸入钢液的多孔炭质喷头，将氩、氮或空气喷入钢包中进行二次精炼。经过炭质喷头净化的气体喷入钢液后，达到控制浇注温度、混匀钢液温度及去除气体和非金属夹杂物的精炼效果。     

Microstructure and sound velocity of Ti-N-O synthetic inclusions in Ti-6Al-4V

The ultrasonic properties of titanium-nitrogen-oxygen inclusions within Ti-6A1-4V (Ti64) blocks were measured and related to inclusion chemistry. Sound velocities were measured on Ti-N-O alloy samples that had been prepared by powder metallurgy and ingot-melting techniques. The contributions to sound velocity from oxygen and nitrogen contents were determined. Then, Ti64 blocks were hot isostatic pressing (HIP) bonded to contain inclusions of the Ti-N-O alloys. The signal-to-noise ratios of reflections from uncracked inclusions were found to be an increasing function of inclusion interstitial content and were related to changes in sound velocity with inclusion chemistry. Measurements were made of the reflectance of titanium-nitrogen inclusions in titanium and Ti64.