Leaching of gallium from corundum flue dust using mixed acid solution

In order to extract gallium from a high-silica-content flue dust generated in corundum production, a mixed acid solution of H₂SO₄ and HF was used for leaching, and test parameters of the leaching process were optimized. Experimental results show that the leaching rate of gallium was only 38% when H₂SO₄ was used as leaching agent. Composition analysis results of micro areas in this corundum flue dust indicate that the content of gallium in silica-enriched phases was high; this portion of gallium was insoluble in H₂SO₄ solution. The leaching rate of gallium increased significantly with addition of HF due to corrosion of silica. Effects of reaction time, temperature, and concentrations of HF and H₂SO₄ on leaching rates of gallium were investigated. The leaching rate of gallium reached 91% when this corundum flue dust was leached in a mixed acid solution of H₂SO₄ and HF for 4 h, at a temperature of 80 °C, with a liquid-to-solid ratio of 5:1 (mL/g). The optimal concentrations of H₂SO₄ and HF in the mixed acid solution were 1.5 and 6.4 mol/L, respectively.     

黄磷电炉电尘浆提取镓的预处理

根据在电炉还原炼磷过程中,磷灰石中的镓在电尘浆中高度富集,成为可供利用的镓资源,提出了一种提取镓的预处理技术:用浓硫酸熟化电尘,将其中的镓先转化成水溶性化合物,再从预处理物料中浸出镓.考察了预处理过程中电尘的化学和矿物学变化以及影响镓提取率的因素,并给出了适宜的预处理条件;在最佳质量比电尘:水:硫酸=1:1:1,200℃下熟化2 h.实验结果表明,在优化条件下将预处理的电尘在80℃浸出1 h,镓的浸出率可达90%以上.     

热处理对粉末冶金Cu-15Ni-8Sn合金组织与性能的影响

以Cu-15Ni-8Sn合金粉为原料制备了粉末冶金试样,研究其在不同的固溶温度、冷压变形、时效温度和时效时间条件下的硬度,着重研究了840℃×15 min固溶+40%冷压变形条件下时效温度和时间对硬度及剪切强度的影响规律,采用金相及扫描电镜分析了相应的微观组织。结果表明,影响Cu-15Ni-8Sn合金硬度的主次因素为:冷压变形量>时效时间>时效温度>固溶温度,较优的工艺参数为840℃×15 min固溶+40%冷压变形+400℃×4 h时效,可获得37.6～38.3 HRC的高硬度和570～628 MPa的抗剪切强度。     

Microstructure and mechanical properties of forged Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy after two-step ageing treatment at 120 and 170℃

The tensile properties,electrical conductivity,and microstructure of the forged Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy were investigated after a two-step ageing treatment at 120 and 170℃.The results indicate that the strength of the alloy reaches the peak value at 170℃ for 1 h during the second step ageing and then decreases sharply.However,the electrical conductivity value increases continuously with the second ageing time increasing.The fracture mechanism of the alloy is intergranular fracture for 1 h and then changes to dimple transgranular fracture later,and the toughness of the alloy is improved significantly.The phases of η' and η are major precipitates in the alloy under the two-step ageing condition.Discontinuous grain boundary precipitates and precipitate-free zones along the grain boundary are clearly observed.     

钼精矿及烟道灰中铼的测定

介绍了钼精矿及烟道灰中铼的酸溶-萃取光度测定法。对溶样、萃取分离、显色、测定等条件进行了系统的试验研究,确定了铼的最佳测定条件。运用此法进行钼精矿及烟道灰中铼的测定,相对标准偏差 (n=11)均小于3.5%。经与其他实验室不同分析方法 (ICP-AES标准加入法、碱熔-萃取光度法)进行数据比对,结果令人满意     

Processing to obtain high-purity gallium

Gallium has become increasingly popular as a substrate material for electronic devices. Aside from ore, gallium can be obtained from such industrial sources as the Bayer process caustic liquor that is a byproduct of bauxite processing, flue dust removed from the fume-collection system in plants that produce aluminum by the electrolytic process, zinc refinery residues, gallium scrap materials, and coal fly ash. The purification process for gallium can start with solvent-extraction processes where the concentrations of impurities, especially metals, are reduced to the ppm range. This article describes how ultra-purification techniques can be employed to reduce the undesirable impurities to the low ppb range. The various procedures described give an idea as to the extent of work needed to obtain and prepare high-purity gallium for electronic application. For more information, contact R.G. Bautista, University of Nevada, Department of Metallurgical and Materials Engineering, Reno, Nevada 89557; e-mail bautista@mines.unr.edu.     

从镍钼矿中提取镍钼的工艺

针对现行镍钼矿处理工艺存在的钼镍需要分别提取的缺陷,提出镍钼矿加钙氧化焙烧-低温硫酸化焙烧-水浸提取镍钼的新工艺。以贵州遵义镍钼矿为原料,对CaO加入量、氧化焙烧温度、氧化焙烧时间、硫酸加入量、硫酸化焙烧温度、硫酸化焙烧时间以及焙砂水浸工艺参数对镍钼浸出率的影响进行研究。结果表明:在最佳工艺条件下,钼的浸出率为97.33%,镍的浸出率为93.16%,且最佳工艺参数为100 g镍钼矿加入35 g CaO,700℃氧化焙烧2 h,得到的焙砂加入70 mL浓硫酸,再经250℃硫酸化焙烧2 h;硫酸化焙烧得到的焙砂按液固比2:1加水搅拌,经98℃浸出2 h。加入CaO不仅能有效减少镍钼矿氧化焙烧烟气对环境造成的污染,而且能显著提高镍的浸出率。     

大功率密闭直流电弧炉冶炼钛渣烟气净化工艺研究

根据国内引进的第一台30MW密闭直流电弧炉钛渣生产线的工艺流程,对采用云南省钛铁矿冶炼钛渣过程中产生的烟气进行了气体及烟尘的流量、含量、化学成分等分析。由于产生的烟气具有温度高、含尘量大(1.75%~9.60%)、SO2含量低、CO含量高的特点,选择烟气净化设备时,除了处理能力要符合生产要求,还需要考虑粉尘粒径和烟气温度这两个因素,以实现烟气回收利用的目的。经过研究,烟气净化工艺首先对烟气进行直接水冷使烟气降温,然后选用德国进口涤气机对烟气进行精处理,除尘效率可以达到99.983%。处理净化后的烟气,热值高,气体性质稳定,净化后可安全用于无烟煤/钛渣干燥及渣包/铁包的烘烤,实现节能减排的目标;烟尘可以回收利用。     

Effects of the two-step ageing treatment on the microstructure and properties of 7B04 alloy pre-stretched thick plates

The effects of the two-step ageing parameters （temperature and time） on the mechanical properties and electrical conductivity of 7B04 （A1-Zn-Mg-Cu） pre-stretched thick plates were studied. The results reveal that the initial T1 ageing contributes a major increase of the tensile strength, and the 0.2% proof stress value reaches 482 MPa after ageing for 7 h at 115℃. Behavioral differences in the tensile properties of the alloy after the two-step ageing treatment were less with the first-step ageing at 115~C for different time periods （7, 14, and 21 h）. The effects of the second ageing parameters on the properties and microstructure of the 7B04 alloy were remarkable. TEM analysis of the samples aged at Temper I （7 h at 115℃ ＋ 12 h at 160℃） and Temper II （7 h at 115℃ ＋ 16 h at 165℃） indicates that two kinds of phases, i.e. 11＇ and 11 phases, precipitate from the matrix and efficiently improve the tensile strength of the alloy, and the grain boundary precipitates are coarse and discrete. There are obvious precipitate free zones （PFZs） along the grain boundary in the microstructure of the alloy after the two-step ageing treatment.     

Mg-4Zn-2Al-0.5Ca合金时效沉淀过程的相演变

利用高分辨透射电镜和扫描电镜分析了Mg-4Zn-2Al-0.5Ca合金时效沉淀过程中的相演变。结果表明:试验合金的时效硬化曲线呈现典型的时效硬化特征。试验合金在160℃时效达到峰值硬度时其沉淀相有:平行于(0001)Mg的圆盘状沉淀相、(梳齿状)块状沉淀相以及大量的亚稳过渡相。随时效时间的延长,生成长条状相,但基体中依然存在很多后析出的细小的弥散分布的粒状沉淀相。120℃×230 h时效处理后的微观组织中存在着蜂窝状组织,宽度为3～4 nm的长条状沉淀相,直径为5～7 nm的球状沉淀相;这些沉淀相的存在大大提高了合金的硬度。     

盐酸蒸馏-磷酸三丁酯萃取法从锗煤烟尘中综合回收锗和镓

先采用二氧化锰氧化-盐酸蒸馏提取煤烟尘中的锗,经提纯后制备得到高纯二氧化锗,同时煤烟尘中的镓在蒸馏过程中充分溶解到了锗蒸馏残渣液中,过滤后镓和蒸馏后残留的锗进入到了蒸馏残液中,调节蒸馏残液的酸度至5.6mol/L,采用磷酸三丁酯的260#溶剂油溶液对镓进行萃取,蒸馏残液中的少量锗亦被同时萃取进入到有机相中,用氢氧化钠溶液进行反萃取,反萃取完后调节pH至6.5~6.7,升温至85~95℃水解,得到氢氧化镓沉淀和二氧化锗沉淀,经过滤烘干后得到含锗镓精矿。锗的蒸馏回收率可达到92.37%以上,残液中锗的萃取率可达到86.18%以上;镓的盐酸浸出率可达81.23%以上,镓的磷酸三丁酯萃取率可达98.81%以上,反萃取率可达99.11%以上,中和沉淀直收率可达93.20%以上;工艺方法具有工艺流程简短、设备简单、过程易于控制,所用生产辅料较少,是一种从煤烟尘中综合回收锗和镓的高效且经济的方法。     

磁控微粉砂轮固化工艺对砂轮磨削性能的影响

目的研究砂轮在固化过程中,固化温度和固化时间对砂轮磨削性能的影响。方法通过测试两种固化工艺制备的砂轮的抗压强度、硬度以及其加工硬质合金YG8的磨削比、表面粗糙度、加工非球面的形状精度随固化温度的变化,来评价固化温度对磁控微粉砂轮磨削性能的影响。结果砂轮的磨削性能与其固化温度、时间有直接关系。磨削比随着固化保温时间的增长呈先增长后下降的趋势。固化温度决定砂轮固化速率和砂轮对过度固化的敏感程度,170℃固化能使砂轮在较短时间达到最佳磨削性能,但是固化时间超过8 h时,其性能会迅速衰减。130℃固化有利于防止砂轮过度固化而造成性能急剧降低。通过对固化工艺的研究,170℃/5 h+130℃/5 h固化工艺下制备的砂轮磨削性能最佳,该砂轮磨削YG8得到最佳的面形精度为365 nm,最佳表面粗糙度为3 nm。结论砂轮在固化过程中,固化温度与固化时间直接影响树脂的固化反应速率与固化程度,通过对固化工艺的实验研究,在本实验条件下得到了最优的固化工艺参数。     

Recovering indium with sulfating roasting from copper-smelting ash

A technology for recovering indium from Jinchuan copper-smelting ash was developed. Indium in the ash was first enriched to the leaching-slag in leaching process,and then recovered by sulfating roasting. The method included mixing the leaching-slag with sulfuric acid,making them into particles,roasting the mixture,and then leaching the calcine with hot water. Above 90% of indium in calcine could be dissolved into the leaching solution. The optimized conditions were determined as follows： the mass ratio of sulfuric acid to leaching slag was 0.1,the roasting time was about 1 to 1.5 h in the temperature range of 200-250℃,and the calcine was leached for 1 h with 5：1 of liquid/solid ratio at 60℃. Over 99% of indium in leaching solution was finally enriched by Zn substitution or sulfide precipitation.     

Cr-Bi对Mg-8Zn-4Al合金铸态组织及时效沉淀相演变的影响

利用扫描电子显微镜(SEM)和X射线衍射(XRD)等分析手段研究了Bi、Cr-Bi复合添加对Mg-8Al-4Zn合金铸态组织及时效沉淀相演变的影响。结果表明:Cr-Bi复合添加能有效改善合金的铸态组织,使连续网状相断开呈短杆或颗粒状。Bi、Cr-Bi复合添加的合金经350℃×12 h+160℃时效,其沉淀硬化曲线呈现典型的温时效。Cr-Bi复合添加的合金时效初期硬化速率较高,20 h就达到峰值硬度的97%,时效48 h达到峰值硬度92.44 HV,过时效阶段硬度下降速度比较缓慢。Mg-8Zn-4Al-0.5Bi合金经350℃×12 h+160℃×120 h时效后主要有MgZn2、Mg3Bi2和单Bi相,呈短杆或细小颗粒状弥散分布在基体上;Cr-Bi复合添加的合金经350℃×12 h+160℃×144 h时效后,除短杆或细小颗粒状的MgZn2相外还有Cr、Al12Cr3等沉淀相,没有发现粗大的MgZn相,且沉淀相与单独添加Bi经120 h时效的合金相比更加细小、致密、弥散均匀分布。     

电子束快速成形TC18钛合金柱状晶组织的拉伸性能

采用电子束快速成形方法,获得了一种TC18钛合金的柱状晶组织,研究了热处理工艺对该类组织析出相和拉伸性能的影响。结果表明,在740～830℃温度范围内固溶、在550℃时效处理,随着固溶温度的升高,快速成形样品沿柱状晶方向的强度呈上升趋势,塑性呈下降趋势;在830℃固溶处理后,在550～650℃时效温度范围内,随着时效温度的升高,沿柱状晶方向的强度呈下降趋势,而塑性呈上升趋势;拉伸性能随热处理工艺的变化主要取决于热处理过程中产生的二次α相;发现了延性韧窝和沿晶+准解理两种不同类型的断口形貌,并对其形成原因进行了分析。     

R-phase transformation of aged Ti-Ni shape memory alloy

Ti-50.6Ni（molar fraction, %） shape memory alloy solution treated at 850 ℃ for lh followed by ageing treatment at 450 ℃ for 3 h was studied with differential scanning calorimetry（DSC）, X-ray diffractometry（XRD） and transmission electron microscopy（TEM）. DSC measurement reveals two separate transformation peaks. XRD and TEM demonstrate that a three-stage transformation occurs. The Ti3 Ni4 precipitates are coherent with the R- phase. The crystal structure of R-phase was analyzed by two diffraction patterns method. The diffraction patterns of R-phase were obtained in detail from the same region.     

A comparative study of Mg-Gd-Y-Zr alloy cast by metal mould and sand mould

The differences of the microstructure and mechanical property between metal mould and sand mould cast Mg-10Gd-3Y-Zr alloy were investigated both under as-cast condition and after solution heat treatment.In the as-cast specimens,the microstructure is similar and composed of α-Mg solid solution and eutectic compound of α-Mg+ Mg24(Gd,Y) 5;whereas the grain size using metal mould and sand mould is 27 μm and 71 μm,respectively.The eutectic compound of metal mould cast alloy was completely dissolved after solution treated at 500℃ for 8 h,however it needs higher temperature(525 ℃) and longer time(12 h) to achieve the absolute dissolving under sand mould condition.In contrast to metal mould,the peak time of sand mould alloy aged at 225 ℃ and 250 ℃ of was advanced by 4 h and 6 h,respectively.The precipitation reaction sequence in sand mould cast Mg-10Gd-3Y-Zr alloy during isothermal ageing at 250 ℃ follows S.S.S.S.→β″(D019) →β'(cboc) →β1(fcc) →β(fcc) ,which is similar to that in the alloy cast using metal mould.     

XPS STUDIES OF OXIDATION BEHAVIOR OF NICKEL AND THERMAL STABILITY OF SURFACE OXIDES

Surface oxidation of polycrystalline nickel foil in air and pure water at different temperaturesand the thermal stability of the surface oxides have been investigated by means of XPS.In ad-dition to NiO,Ni_2O_3 is formed especially after long periods of air exposure.Nickel surfacesare much less reactive to pure water than to air.The thermal stability of the surface oxides isrelated to oxidative temperature.The surface species of oxides formed by air exposure attemperatures below 120℃ can be reduced into nickel metal after heating the sample in vacuumat 300℃ for only 10 minutes (in the case of room temperature) to 1 h (in the case of 120℃).This reduction is caused by reaction with surface carbon contaminants.However,the surfacespecies of nickel oxides formed by air exposure with heating at temperatures above 200℃ cannot be reduced into metal after heating the sample in vacuum at 300℃ for 1h.     

硫化锌银精矿富集银的工艺研究

基于国内外硫化锌矿处理的火、湿法研究进展,对含锌银精矿采用硫酸化焙烧、稀硫酸浸出工艺脱除锌、富集银,考察了焙烧和浸出过程中的主要影响因素。结果表明,硫酸配比为150%,在300℃焙烧90 min,以5%稀硫酸为浸出剂,液固比8:1,搅拌转速200~300 r/min,85℃浸出120 min,最终锌的浸出率可达到98%以上,浸出渣中银含量为7.24%,银被富集7倍。     

硅业工业硅电炉的收尘设计

根据二期工业硅电炉的烟气特性,设计采用表面冷却器、粗分离器、布袋收尘整套收尘工艺对烟气进行综合治理.结合实际生产运行的情况,阐述了收尘设计的主要参数及主要设备,分析了烟气治理的效果,提出了改进措施.