Extraction of valuable metals from low nickel matte by calcified roasting-acid leaching process

A calcified roasting-acid leaching process was developed as a highly effective method for the extraction of valuable metals from low nickel matte in the presence of CaO additive. The influences of process parameters on the metal extraction were studied, including the roasting temperature, roasting time, addition of CaO, H2SO4 concentration and liquid-solid ratio. Under the optimum condition, 94.2% of Ni, 98.1% of Cu, 92.2% of Co and 89.3% of Fe were recovered. Additionally, 99.6% of Fe was removed from the leachate as goethite by a subsequent goethite iron precipitation process. The behavior and mechanism of CaO additive in the roasting process was clarified. The role of CaO is to prevent the formation of nonferrous metal ferrite phases by a preferential reaction with Fe2O3 during the roasting process. The metal oxides(Cu O and NixCu1-xO) remained stable during high-temperature roasting and were subsequently efficiently leached using a sulfuric acid solution.

Researches on the problems in the production of low nickel austenitic stainless steel

Problems encountered in the production of low nickel austenitic stainless steel have been studied. These problems primarily include the changes to the microstructure of the slab during the heating process, the formation and removal of deformation - induced martensite during cold rolling, and the effects of the annealing process on the surface oxide structure. A reasonable manufacturing process has been proposed on the basis of the research results and high-quality cold-rolled strips of low nickel austenitic stainless steel have been produced.

Synthesis of nickel ferrite precursors from low grade nickel matte

Fine nickel ferrite precursors NiFe2（C204）3·6H2O were obtained via co-precipitation method with low grade nickel matte as the raw material. Thermodynamic analysis of NiClz-FeC12-（NH4）2C204-H20 system for precipitation identified that the theoretical optimum co-precipitation pH value is 2, and C2O2 has strong complexation with Ni2＋ and Fe2＋ ions. Based on these theoretical considerations, the effects of parameters on the precipitation rates and precursors size were investigated systematically. The results show that the optimum co-precipitation conditions are pH=2, temperature 45 ℃, 1.2 times theoretical amount of （NH4）2C204 dosage and 3% PEG400 addition. Under these conditions, the precipitation rates of Ni2＋ and Fe2＋ are both over 99.8%, with the precursors size of 1-2 urn. Furthermore, X-ray diffraction （XRD） and thermogravimetry-differential thermal analysis （TG-DTA） demonstrate that the precursors are single-phase solid solution, wherein the nickel/iron atoms are replaced by the iron/nickel atoms reciprocally.

TEMPERATURE EFFECT ON LOW-CYCLE FATIGUE BEHAVIOR OF NICKEL-BASED SINGLE CRYSTALLINE SUPERALLOY

The low-cycle fatigue （LCF） behavior of a nickel-based single crystal superalloy with [001] orientation was studied at an intermediate temperature of T0℃ and a higher temperature of To ＋ 250℃ under a constant low strain rate of 10^-3 s^-1 in ambient atmosphere. The superalloy exhibited cyclic tension-compression asymmetry which is dependent on the temperature and applied strain amplitude. Analysis on the fracture surfaces showed that the surface and subsurface casting micropores were the major crack initiation sites. Interior Ta-rich carbides were frequently observed in all specimens. Two distinct types of fracture were suggested by fractogaphy. One type was characterized by Mode-I cracking with a microscopically rough surface at To ＋ 250℃. Whereas the other type at lower temperature T0℃ favored either one or several of the octahedral {111} planes, in contrast to the normal Mode-I growth mode typically observed at low loading frequencies （several Hz）. The failure mechanisms for two cracking modes are shearing of γ＇ precipitates together with the matrix at T0℃ and cracking confined in the matrix and the γ/γ＇interface at To - 250℃.

HIGH-TEMPERATURE LOW CYCLE FATIGUE BEHAVIOR OF NICKEL BASE SUPERALLOY GH536

Low cycle fatigue tests on nickel base superalloy GH536 were performed at 600, 700 and 800℃. The strain-life and cyclic stress-strain relationship were given at various temperatures. The change in fatigue life behavior and fatigue parameters with tem- perature increasing was discussed. At low and intermediate total strain amplitudes, the fatigue life was found to decrease with increasing temperature.

Realization of Low Temperature Densification of Nickelate Ceramics for MLCC Application

We report an improved method for the preparation of highly dense nickelate ceramics at relatively low temperature. It is found that the introduction of appropriate additives during the ball-milling process facilitates the formation of nickelate phase through solid state reaction. Moreover, although high-purity nickelate powders can only be obtained by calcining the mixture of starting materials at temperature higher than 1100 ℃. The adoption of powders calcined at 1000 ℃, rather than those calcined at higher temperature, is conductive to the low-temperature densification of nickelate ceramics, which is attributed to the small and dispersive particles, and the solid state reaction of the residual starting materials during sintering. Compared with the conventional process, the improved method can reduce the sintering temperature of nickelate ceramics by about 100 ℃ and decrease the grain size of the obtained ceramics, and therefore makes nickelate meet the fabrication requirements of multi-layer ceramic capacitors（MLCC）.

Determination of Nickel and Palladium in Environmental Samples by Low Temperature ETV-ICP-OES Coupled with Liquid-liquid Extraction with Dimethylglyoxime as Both Extractant and Chemical Modifier

A novel method for the determination of nickel and palladium in environmental samples by low temperature ETV-ICP-OES with dimethylglyoxime（DMG） as both the extractant and chemical modifier has been developed. In this study, it was found that nickel and palladium can form complexes with dimethylglyoxime（0. 05%, mass fraction） at pH 6.0 and can be extracted into chloroform quantitatively. The complexes can be evaporated into plasma at a suita-ble temperature（ 1400℃） for ICP-OES detection. Under the optimized conditions, the detection limits of nickel and palladium are 0.48 and 0. 40 ng/mL, respectively, while the RSD values are separately 5.0% and 3.1% （p = 50 ng/mL, n = 7）. The proposed method was applied to the determination of the target analytes in environmental sam-ples with satisfactory results.

A CRYSTALLOGRAPHIC MODEL FOR THE ORIENTATION DEPENDENCE OF LOW CYCLIC FATIGUE PROPERTY OF A NICKEL-BASE SINGLE CRYSTAL SUPERALLOY

Fully reversed low cyclic fatigue (LCF) tests were conducted on [0 0 1], [0 1 2], [(1) over bar 1 2], [0 1 1] and [(1) over bar 1 4] oriented single crystals of nickel-bared superalloy DD3 with different cyclic strain rates at 950 degrees C. The cyclic strain rates were chosen as 1.0 x 10(-2), 1.33 x 10(-3) and 0.33 x 10(-3) s(-1). The octahedral slip systems were confirmed to be activated on all the specimens. The experimental result shows that the fatigue behavior depends an the crystallographic orientation and cyclic strain rate. Except [0 0 1] orientation specimens, it is found from the scanning electron microscopy(SEM) examination that there are typical fatigue striations on the fracture surfaces. These fatigue striations are made up of cracks. The width of the fatigue striations depends on the crystallographic orientation and varies with the total strain range. A simple linear relationship exists between the width and total shear strain range modified by an orientation and strain rate parameter. The nonconformity to the Schmid law of tensile/compressive flaw stress and plastic behavior existed at 95 degrees C, and an orientation and strain rate modified Lall-Chin-Pope ( LCP) model was derived for the nonconformity. The influence of crysrallographic orientation and cyclic strain rate on the LCF behavior can be predicted satisfactorily by the model. In terms of an orientation and strain rate modified total strain range, a model for fatigue life was proposed and used successfully to correlate the fatigue lives studied.

CMQL和UEV下Incone1690镍基合金切削力和温度分析

低温微量润滑(CMQL)可以使切削阶段达到更优的切削摩擦性能,提升刀具耐磨性能并获得更优减磨效果;超声椭圆振动(UEV)能够提高难加工合金的切削性能。在超声椭圆振动基础上设置低温微量润滑条件,并通过实验分析其切削效果。研究结果表明:采用UEV和CCMQL模式时,切削力与进给力降低比例依次为62.3%与75.0%,在低温微量润滑过程能够实现更低温度控制效果,有效防止工件的热软化问题。普通切削时温度都接近445℃。UEV可以获得更低温度,同时运用UEV和CMQL处理方式,温度下降了16.1%,采用UEV和CCMQL方式时,温度下降19.5%。通过降低喷嘴角度的方式,获得更低切削雾滴温度,刀尖应力出现降低实现刀具保护,促进刀具寿命延长。该研究有助于改善合金切削工艺,对提高切削质量提供了一个思路。

镍/木棉纤维衍生碳复合材料的制备及吸波性能研究

近年来,生物质碳因成本低廉、易制备、理化性能优异和具有多孔结构被广泛应用于吸波领域。然而,其吸波性能仍然受较高电导率引发的不良阻抗限制。在此,使用镍(Ni)改性木棉纤维,并使用不同的碳化温度获得镍/木棉纤维衍生碳(Ni/C)复合材料。扫描电镜结果表明,随着碳化温度的升高,Ni颗粒的尺寸增加,且木棉纤维表面出现更多的缺陷结构。XRD和XPS结果证明了Ni和木棉纤维衍生碳的成功复合。Raman结果表明碳化温度的升高导致碳组分石墨化程度增加,提高了复合材料的传导损耗能力。最后,我们将复合材料与石蜡以5∶95的超低填充比例混合,Ni/C-800展现出-52.6 dB的反射损耗值和8.32 GHz的有效吸收带宽。复合材料优异的吸波性能取决于衰减能力和阻抗匹配的协同、介电损耗和磁损耗的共同作用以及大比表面积和中空多孔结构造成的多重散射能力的增强。

高铁低品位红土镍矿酸浸工艺研究

研究了用硫酸从印尼某高铁低品位红土镍矿中加压酸浸镍、钴、铁,并探讨了浸出渣中铁品位变化及常压、加压下的浸出动力学。结果表明:在酸矿比260 kg/t、温度250℃(对应水蒸气压力4.0 MPa)、液固体积质量比3/1、搅拌速度300 r/min、粒度100目、反应时间1 h条件下,镍、钴、铁浸出率分别为98.1%、98.3%、4.7%,铁品位可达51.3%;加压和常压下,镍、钴浸出过程均符合界面化学反应控制的收缩核模型,加压下反应活化能分别为116、91 kJ/mol,常压下反应活化能分别为41、53 kJ/mol;常压下主要是针铁矿的浸出,高压下主要是铬铁矿、磁铁矿等矿相的浸出。

镍基高温合金超声低频振动辅助钻孔试验

采用超声钻孔能够有效缓解轴向力作,提升孔屑排斥效果。为了提高镍基高温合金的钻孔质量,以Inconel718镍基高温合金为例开展超声低频振动辅助钻孔试验研究,完成系统超声低频振动测。钻孔试验结果表明:相比较普通钻孔,超声低频振动钻孔的轴向力与扭矩均值相对常规钻孔方式下降比例为10%~15%;超声低频振动钻孔原先螺旋切屑转变为许多断屑物,促进断屑并快速排出,获得稳定钻孔效果。该研究对提高Inconel 718镍基高温合金板的钻孔质量具有很好的实际应用价值。

Ni@SiO_(2)合成方法对催化剂结构及其双环戊二烯加氢性能的影响

JP-10燃料主要成分挂式四氢双环戊二烯(exo-THDCPD)一般通过双环戊二烯(DCPD)加氢及异构化合成,DCPD的饱和加氢是关键步骤,因此DCPD加氢催化剂的合成尤为重要。基于此,以六水合硝酸镍和硅溶胶为原料,分别通过蒸氨法、沉积法、凝胶法、浸渍法制备出镍质量分数为30%的Ni@SiO_(2)催化剂,应用于DCPD加氢制备四氢双环戊二烯(endo-THDCPD)的反应中。经表征分析发现,通过蒸氨法制备层状硅酸镍结构的前躯体,再经焙烧还原得到的Ni@SiO_(2)催化剂,具有L酸酸量高、Ni纳米级分散、介孔丰富的特点,这使其在DCPD加氢反应中展现出优异的催化活性。当反应温度为25℃时,DCPD加氢转化率为99.9%,endo-THDCPD收率高达99.9%。

高温氧化对粉末高温合金微观结构和疲劳性能影响研究

为了探究涡轮盘用粉末高温合金表面氧化对其低周疲劳性能的影响,分别针对第三代镍基粉末高温合金的粗晶(Coarse grain,CG)和细晶(Fine grain,FG)材料开展氧化时间对其疲劳性能影响机理的研究。通过在700℃空气环境下开展不同时长的高温预氧化实验和低周疲劳(Low-cycle fatigue,LCF)实验,使用SEM和EDS表征LCF断口、表面氧化层结构成分及其强化相形貌变化,揭示LCF裂纹萌生机理。实验结果表明,氧化层厚度随氧化时间而增加,氧元素以氧化侵入的形式进入基体;相同氧化时间下,CG抗氧化性能优于FG;疲劳裂纹萌生于氧化侵入和亚表面夹杂物等应力集中部位,在实验温度下LCF寿命受氧化作用和夹杂物共同影响;高温氧化作用下氧化层呈现分层结构,外层为NiO,中间层为含有Cr_(2)O_(3),TiO_(2)等复杂氧化物及尖晶石相(NiCr_(2)O_(4))的混合层,内层为Al_(2)O_(3);CG二次γ’相氧化后平均尺寸增加,FG二次γ’相平均尺寸没有明显的变化,但两种组织氧化后在晶界附近均观察到长条状的二次γ’相,表明高温氧化作用下晶界优先遭到破坏。

新型高锰低镍奥氏体不锈钢性能研究

以传统304奥氏体不锈钢和新型低镍304X奥氏体不锈钢为研究对象,采用力学及腐蚀实验方法,测试研究了304与304X材料在不同温度下的屈服强度、抗拉强度、冲击韧性及室温下的腐蚀速率。试验结果表明:这种以低成本的氮部分代替昂贵镍的新型奥氏体不锈钢具有较高的强度以及优良的室温韧性,但其低温韧性不足;新型奥氏体不锈钢304X具有与304相媲美的耐蚀性及更好的耐晶间腐蚀倾向,这使其在一些高强度以及低温韧性要求不高的工况中具有良好的应用前景。

铝合金阳极氧化膜低温无镍封孔工艺及其封孔性能

为克服传统沸水封孔高能耗和镍盐封孔污染环境的不足,研制了一种无镍低温封孔工艺,其工艺为:锂盐20~30 g/L,氟锆酸盐3.0~5.0 g/L,表面活性剂1.0~2.0 g/L,有机添加剂N 2.0~4.0 mL/L,温度35~55℃,pH 5.0~5.4,封闭时间宜控制在2~3 min/μm。通过酸浸蚀失重试验和电化学试验法对封孔质量和封孔膜的耐蚀性进行评价。结果表明:采用配制的低温无镍封孔剂进行封闭,膜层酸浸蚀失重<30 mg·dm-2,电化学性能明显改善,其封孔效果优于沸水封孔,略差于常温镍盐封孔。

制孔工艺对DD6镍基单晶高温合金低周疲劳性能的影响

在900℃、540 MPa条件下,研究了电液束加工、电火花成形加工、电火花小孔加工三种制孔工艺对DD6单晶高温合金试验件低周疲劳性能的影响,并对孔微观形貌和断口形貌进行了对比分析。结果表明,在相同试验条件下,电液束加工得到的气膜孔具有最佳的疲劳寿命。疲劳源位于气膜孔周边,不同制孔工艺的断口特征相似,均为多源断裂,而断口主要包括疲劳裂纹源区、扩展区和瞬断区三个区域。

屈服强度500MPa级耐候焊丝焊缝的强韧化机制

采用ER65NH-A焊丝对Q500qENH钢进行了CO_(2)保护焊。分析了焊丝的Ni含量与焊缝的显微组织和力学性能之间的关系。结果表明:当焊丝的Ni质量分数从0.78%增加至1.65%时,焊缝抗拉强度从706 MPa提高到了732 MPa,屈服强度从579 MPa提高到了614 MPa,-40℃冲击吸收能量(KV2)从46 J提高到了84 J。焊缝力学性能改善的机制为:Ni含量的增加提高了奥氏体的稳定性,细化了焊缝柱状晶区和焊道热影响区组织,焊缝发生脆性断裂的倾向减小。

GH4169合金低温渗硼层结构与耐磨性能研究

GH4169合金因具有良好的高温强度及耐腐蚀性等,在航空航天领域应用广泛,但其也存在表面硬度低、耐磨性差的问题。固相渗硼是提高GH4169合金耐磨性能的有效手段,但常用渗硼工艺普遍采用900℃以上高温,这会破坏合金时效处理所得到的析出相结构。本实验将GH4169合金热处理时效过程与渗硼过程相统一,通过引入ZrO_(2)作为新型催渗剂获得了厚度约8.2μm的致密渗硼层。分析发现渗硼层由Cr_(5)B_(3)、Cr_(2)B、Ni_(2)B和FexNi_(23-x)B_(6)复合相组成,表面硬度高达2622.9 HV0.1,并在与氮化硅球对磨时呈现出极低的磨损率值,即8.5×10^(-6)mm^(3)/(N·m)。

高钼含量镍基合金低成本非真空感应炉冶炼

基于抚顺特殊钢股份有限公司镍基合金生产平台,研究了“30 t非真空感应炉-炉外精炼-电渣重熔”工艺代替传统高成本工艺冶炼高钼含量镍基合金的可行性,并结合生产实际分析了生产效率和成本优势。结果表明,采用30 t非真空感应炉熔炼钢水,VOD吹氧脱碳后抽真空至67 Pa以下脱气冶炼工艺方案,成功实现了高钼含量镍基合金N06625、N10276产品的冶炼。电渣后的钢锭生产为204 mm锻材产品,化学成分、非金属夹杂物均满足行业标准要求,进一步提高了高钼镍基合金的生产保障及成本控制能力。