硫酸锌和碳酸钠抑制滑石浮选机理（英文）

通过浮选试验、溶液化学计算和多种表征技术,深入研究硫酸锌和碳酸钠在黄铜矿和辉钼矿浮选中对滑石的抑制机理。浮选试验表明,在pH值为7～9的范围内滑石浮选得到有效抑制。在该pH范围内,对硫酸锌和碳酸钠混合溶液的溶液化学计算表明,碱式碳酸锌是主要的含锌物种;X射线衍射和红外光谱分析进一步证明了这一点。Zeta电位测试表明：在滑石抑制发生的pH范围内,碱式碳酸锌表面带正电荷,而滑石表面带负电荷。X射线光电子能谱和场发射扫描电子显微镜证实：经硫酸锌和碳酸钠混合溶液处理的滑石颗粒表面存在含锌沉淀物。结果表明,由于静电吸引,形成的碱式碳酸锌与滑石发生异相聚沉,从而抑制滑石浮选。     

葡聚糖对辉钼矿与滑石浮选分离的影响

通过动电位分析、润湿接触角测试、吸附量测试并结合浮选实验,考察滑石和辉钼矿单矿物的浮选行为,以葡聚糖为抑制剂,研究硫化矿体系中辉钼矿和滑石的浮选分离。结果表明:在无捕收剂情况下,辉钼矿和滑石的天然疏水性强,可浮性相似,难以实现浮选分离。加入的葡聚糖在辉钼矿和滑石矿物表面形成选择性吸附,使两者具有不同的浮选行为。当溶液p H为8.5、葡聚糖用量400 mg/L时,辉钼矿可以得到有效抑制,回收率仅为14.37%,而滑石受到的抑制作用较弱,其回收率为83.22%,两者的浮游差为68.85%,这使得滑石和辉钼矿的浮选分离成为可能。     

蛇纹石抛光工艺的研究

以试验为基础研究了蛇纹石的抛光工艺,并对各种抛光条件对表面光泽度的影响进行了探讨。结果表明,选用合适的抛光剂、抛光时间、预加工光泽度、冷却方式及抛光工具材料,光泽度可达90以上。此抛光工艺简单、经济、高效。     

酸性体系中蛇纹石矿泥的抑制及其对硫化铜镍矿浮选的影响

为了消除硫化铜镍矿物表面的氧化膜,抑制蛇纹石等含镁脉石矿泥对浮选影响,在硫化铜镍矿的酸性浮选工艺的基础上研究了羧甲基纤维素(CMC)对硫化铜镍矿浮选过程的优化效果,并探讨了CMC的作用机理。结果表明:1×10^?3 mol/L盐酸溶液及20 min超声预处理可以显著强化硫化铜镍矿的可浮性,酸性浮选体系可以在更宽的pH范围内取得较好的回收率;在pH=3的酸性体系中添加20 mg/L CMC,硫化铜镍矿浮选精矿镍品位提高至19.42%,回收率提高至60.05%;分别比同等条件下不添加CMC的浮选指标分别提高了1.78%和22.79%;CMC对蛇纹石矿泥选择性抑制是其优化硫化铜镍矿浮选过程的主要原因;浊度及表面动电位测试表明CMC加入量必须控制于20 mg/L以内,过量的CMC产生有团聚作用,不利于矿泥颗粒间的分散。     

六偏磷酸钠在蛇纹石与黄铁矿分离中的作用

通过浮选试验、沉降试验、表面溶解、ζ电位测试、吸附量测试和红外光谱测试研究六偏磷酸钠在蛇纹石与黄铁矿分离中的作用与机理。结果表明,六偏磷酸钠可以显著减弱蛇纹石对黄铁矿浮选的不利影响,它能在碱性条件下使蛇纹石与黄铁矿分散,从而提高黄药在黄铁矿表面的吸附量。六偏磷酸钠的作用是通过溶出蛇纹石表面的镁,并在其表面吸附,降低蛇纹石表面等电点pH,增强负电性。DLVO理论计算表明,六偏磷酸钠能使蛇纹石与黄铁矿间的总相互作用能由引力位能转变为斥力位能。     

微细粒蛇纹石的可浮性及其机理

通过浮选实验、润湿接触角测定、Zeta电位测试和泡沫水回收率测定,考察pH值、样品粒度、矿浆浓度和起泡剂种类与用量等因素对金川硫化铜镍矿中的主要脉石矿如微细粒蛇纹石可浮性的影响,并对其机理进行分析.结果表明:蛇纹石的润湿接触角为37.6-,属于亲水性矿物,天然可浮性差;随着蛇纹颗粒粒度的减小以及矿浆浓度的增大,其浮选回收率升高;起泡剂对蛇纹石的表面电性和润湿性影响不大,而在微细粒蛇纹石的浮选中,不同起泡剂种类和用量下的泡沫水回收率与矿物浮选回收率具有良好的对应关系,可以推测泡沫夹带是蛇纹石浮选进入精矿的重要原因.     

钨酸钠对镍黄铁矿与蛇纹石浮选分离的影响及作用机理

针对浮选时镍黄铁矿和蛇纹石易产生异质凝聚而造成其浮选分离难的问题,研究发现添加钨酸钠可实现镍黄铁矿和蛇纹石的有效分离。通过纯矿物浮选试验、浊度试验、Zeta电位测试、浮选溶液化学及X射线光电子能谱(XPS)分析,研究了钨酸钠对镍黄铁矿与蛇纹石浮选分离的影响及作用机理。结果表明：加入钨酸钠后,镍黄铁矿与蛇纹石单矿物的浮游差由69.02%升高至81.28%,人工混合矿中镍黄铁矿回收率升高至83.56%,表明添加钨酸钠可促进镍黄铁矿与蛇纹石浮选分离;钨酸钠的加入使蛇纹石和镍黄铁矿的浊度值升高,表明二者之间的分散作用增强。钨酸钠在溶液中主要以WO₂^4-形式存在,可吸附在镍黄铁矿和蛇纹石表面,使二者表面均荷强负电,增强了二者之间的静电斥力,从而减弱二者的异质凝聚。WO₂^4-在镍黄铁矿表面发生化学吸附,且其吸附强度强于蛇纹石表面的吸附强度。     

工艺参数对铝合金微弧氧化膜层蛇纹石含量的影响

为探究工艺参数对铝合金微弧氧化膜层中蛇纹石含量的影响,采用微弧氧化技术,分别在双向恒压、单向恒压和单向恒流模式下,在添加蛇纹石微纳米颗粒的电解液中进行试验,在ZL109铝合金表面原位生长陶瓷层。采用SEM、EDS及XRD对膜层进行分析。结果表明:在单向恒压和单向恒流模式下制得的微弧氧化膜层的蛇纹石含量相比双向恒压模式分别提高了92%和113%;微弧氧化膜层中的蛇纹石含量随电流的增加而增加,随频率的增加而降低,随电解液中蛇纹石微纳米颗粒浓度的增加而增加;试验过程中试样与电解槽之间的电场产生的电泳效应,使得在电解液中呈电负性的蛇纹石微纳米颗粒移动到试样表面,在接触到试样表面熔融态的高温氧化物时,蛇纹石微纳米颗粒表面熔化而粘合在试样表面,经电解液冷却复合到了微弧氧化膜层中。     

羧甲基纤维素对层状镁硅酸盐矿物浮选的抑制与分散作用

通过浮选实验、润湿接触角测量和Zeta电位测试,考察滑石、绿泥石和蛇纹石3种层状镁硅酸盐矿物的可浮性及其对金川镍矿中的硫化矿物-黄铁矿浮选的影响,并研究羧甲基纤维素(CMC)对3种层状镁硅酸盐矿物浮选的抑制与分散作用.结果表明;3种镁硅酸盐矿物表面性质与可浮性不同,对硫化矿浮选的影响方式与机理也存在区别:蛇纹石天然可浮性较差,但由于静电作用易与黄铁矿发生异相凝聚,降低黄铁矿的可浮性进而影响其回收率,CMC可通过调整矿物表面电性而起到分散作用;滑石与绿泥石并不影响黄铁矿的可浮性,但由于其天然可浮性相对较好,易进入精矿增加MgO杂质含量,CMC能调整矿物表面润湿性而抑制其浮选.     

蛇纹石酸浸渣碱溶脱硅反应动力学

以蛇纹石酸浸渣为原料,系统研究了碱溶脱硅反应动力学。通过X射线衍射(XRD)、X射线荧光(XRF)、热重-差热(TG-DTA)和场发射扫描电镜-能谱(FESEM-EDS)对蛇纹石酸浸渣物相、化学组成、热稳定性及形貌结构进行了详细分析。利用单因素变量法对蛇纹石酸浸渣碱溶脱硅反应过程进行了研究,详细讨论了NaOH质量分数、反应温度、液固比、搅拌速度和粒度对酸浸渣中SiO₂溶出率的影响,并分别采用收缩核模型及Avrami方程拟合动力学,并建立了反应动力学方程。结果表明：在该体系中,蛇纹石酸浸渣碱溶过程动力学不符合传统的收缩核模型,而符合Avrami方程且拟合相关性较高;整个溶出过程受扩散控制,模型特征参数n₁=0.21,反应表观活化能E_a=8.62 kJ/mol。     

Mechanisms of surface charge development of serpentine mineral

The electrokinetic behavior and surface dissolution of serpentine mineral were studied through Zeta potential measurements, dissolution experiments and X-ray photoelectron spectroscopy. The results show that serpentine has an iso-electric point (IEP) of 11.9, which is higher than that of other phyllosilicate minerals. Dissolution experiments show that the hydroxyl is easy to dissolve with respect to the magnesium cations in the magnesium oxide octahedral sheet. As a result of hydroxyl dissolution, the magnesium ions are left on serpentine surface, which is responsible for serpentine surface charge. The removal of magnesium ions from serpentine surface by acid leaching results in a decrease of serpentine IEP. Therefore, it has been clearly established that the surface charge developed at the serpentine/aqueous electrical interface is a function of the serpentine surface incongruent dissolution.     

Effect of serpentine and sodium hexametaphosphate on ascharite flotation

Sodium hexametaphosphate (SHMP) was used to minimize the adverse effect of serpentine for improving ascharite recovery. The effects of particle size and content of SHMP, and serpentine on ascharite flotation process were investigated through flotation, zeta potential tests, FT-IR analysis, XPS analysis and DLVO theory. Particles interaction and mechanism of SHMP were also discussed. It was found that aggregation between serpentine and ascharite particles easily happened, and the particle size of serpentine had a profound impact on the ascharite recovery. In particular, the fine serpentine with size less than 38 μm had the greatest contribution to the deterioration of ascharite flotation performance. After SHMP treatment, the adverse effect of serpentine was significantly reduced. The mechanism of SHMP showed that it could alter the surface charges of serpentine and ascharite to prevent severe interparticle aggregation, which resulted in a well-dispersed pulp and benefited ascharite flotation process. The adsorption of SHMP on serpentine was due to hydrogen bonding and chemical adsorption, resulting in the formation of complex on serpentine surface to decrease its floatability.     

采用蛇形通道浇注法制备半固态6061铝合金浆料

采用蛇形通道浇注工艺制备半固态6061铝合金浆料.研究浇注温度、弯道数量和弯道内径对显微组织的影响,并分析半固态浆料在浇注过程中的显微组织演变机理.结果表明:控制浇注温度在液相线附近可以细化晶粒、提高晶粒圆整度,并且增加弯道数量和降低弯道内径可以有效增加初生α(Al)晶粒的形核率.初生晶粒不仅由合金熔体受激冷形核和异质...     

Flotation separation of molybdenite and talc using tragacanth gum as depressant and potassium butyl xanthate as collector

Tragacanth gum (TG) was explored as a depressant to realize the flotation separation of molybdenite and talc. The flotation experiments indicated that when using potassium butyl xanthate (PBX) as a collector, molybdenite showed excellent floatability while talc was completely depressed by TG, thus realizing the flotation separation of the two minerals. X-ray photoelectron spectroscopy (XPS) analysis results showed that TG was adsorbed on molybdenite surface via chemisorption. The results of contact angle measurement, Fourier transform infrared (FTIR) spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) indicated that the pre-adsorption of TG on molybdenite could not hinder the further chemisorption of PBX on molybdenite. Because PBX has no collecting ability on talc, the flotation separation of molybdenite and talc came true using PBX to collect molybdenite and TG to depress talc.     

Enhancement of pentlandite surface magnetism and implications for its separation from serpentine via magnetic separation

The magnetism of pentlandite surface was enhanced through the selective precipitation of micro-fine magnetite fractions on pentlandite surfaces. This was achieved through adjustment of slurry pH and addition of surfactants. The results showed that at pH 8.8 with the addition of 100 g/t sodium hexametaphosphate, 4.5 L/t oleic acid, and 4.5 L/t kerosene, significant amount of fine magnetite particles adhered to the pentlandite surface, while trace amount of coating was found on serpentine surfaces. Thus, the magnetism of pentlandite was enhanced and pentlandite was well separated from serpentine by magnetic separation under the magnetic field intensity of 200 kA/m. Scanning electron microscopy (SEM) and zeta potential measurement were performed to characterize changes of mineral surface properties. Calculations of the extended Derjaguin–Landau–Verwey–Ocerbeek (EDLVO) theory indicated that, in the presence of surfactants the total interaction energy between magnetite and pentlandite became stronger than that between magnetite and serpentine. This enabled the selective adhesion of magnetite particles to pentlandite surfaces, thereby enhancing its magnetism.     

采用蛇形通道制备较大容量A356铝合金半固态浆料(英文)

采用蛇形通道制备较大容量的A356铝合金半固态浆料,对制备的半固态浆料的整体组织和管道冷却能力对组织的影响进行研究。结果表明,采用冷却能力良好的蛇形通道可制备出理想的较大容量半固态A356铝合金浆料。蛇形通道连续通冷却水时,较大容量半固态A356铝合金浆料轴向和径向的组织均由颗粒状的初生相组成,浆料的整体均匀性良好;而未通冷却水的蛇形通道只能在较大容量浆料的心、中部获得颗粒状初生相,靠近浆料的边部区域则主要为树枝状初生相,整个浆料径向的组织不均匀。浇注温度达到680°C,可以解决合金熔体在浇注过程中容易堵塞的问题。     

蛇形通道浇注制备半固态7075铝合金浆料(英文)

采用蛇形通道浇注技术制备半固态7075铝合金浆料,研究浇注温度和弯道数量对半固态7075铝合金浆料微观组织的影响。结果表明:当浇注温度为680~700°C时,可以制备出质量较好的半固态7075铝合金浆料;在相同浇注温度条件下,随着弯道数量的增加,初生α(Al)的平均晶粒尺寸减小,形状因子提高。在浇注制备半固态7075铝合金浆料过程中,合金熔体在具有一定弧度且封闭的蛇形弯道内流动并多次改变流动方向,具有类似"搅拌"的功能,使得初生晶核逐渐演变为球形或近球形晶粒。     

Investigation on addition of talc on sintering behavior and mechanical properties of B4C

The effect of high alumina talc powder as a sintering aid on densification of boron carbide powder was investigated. The in situ reaction of talc with boron carbide generate SiC, MgB₂, and alumina, which all aid the sintering process and permit pressureless sintering at temperatures between 2050 and 2150°C. The microstructure-property relationship has been studied in the B₄C-talc system for talc content between 0 and 30 wt.%. It became clear the addition of talc powder has a significant effect on the sintering behavior of B₄C. B₄C composites along with talc powder additions were sintered up to 98% of theoretical density. The mechanical properties were improved over those of samples without talc addition.