氟离子选择电极法测定稀土-镁中间合金中的氟

采用氟离子选择电极法测定了稀土-镁中间合金中的氟含量,稀土和镁基体对氟的测定干扰严重,以氢氧化钠将基体沉淀分离后,过量氢氧化钠造成的二次干扰需以标准加入法消除。试验确定的最终条件为,以30%氢氧化钠将基体沉淀分离,控制溶液pH值为5～6,以TISAB缓冲溶液调节溶液离子强度,由标准曲线确定一定温度下的斜率S,不使用格氏作图纸,以单点标加法测定并计算合金样品中氟的含量。     

Na2EDTA返滴定法测定铜冶炼烟尘中镉

铜冶炼烟尘中含有较高含量的铅、铜、砷、铝、铁、锑、铋等元素,对滴定法测镉产生干扰。采用氟化铵-盐酸-硝酸-高氯酸分解试样,用氢溴酸除去砷、锑、锡等干扰元素。硫酸铅沉淀分离铅,氨水沉淀分离铁、铋、部分铝等共存元素,在稀硫酸介质中加入硫代硫酸钠使铜离子以硫化亚铜状态从溶液中分离,滤液中加入过量的Na₂EDTA标准滴定溶液,加入氟化钾掩蔽剩余铝,在pH 5.5~5.6的盐酸-六次甲基四胺缓冲溶液中,以二甲酚橙为指示剂,用锌标准滴定溶液返滴定。测得结果为锌、镉合量,扣除锌量,即为镉量。优化了氨水用量、氟化钾用量等实验条件,建立了Na₂EDTA返滴定法测定铜冶炼烟尘中镉含量的方法。方法用于测定铜冶炼烟尘中镉,结果与电感耦合等离子体原子发射光谱法(ICP-AES)一致,结果的相对标准偏差(RSD,n=11)为0.56%~0.92%。按照实验方法对铜冶炼烟尘样品进行加标回收试验,回收率为99.6%～100.2%。     

铝土矿中S2-含量的测定

依据拜耳法生产氧化铝高压溶出原理,同时结合铝土矿中的以黄铁矿、褐铁矿形式存在的硫在280℃高温高压条件下可与氢氧化钠作用生成硫化钠进入溶液的实验条件,在溶出液中加入盐酸酸化,生成硫化氢气体用镉盐溶液吸收,在吸收液中,加入过量的碘标准溶液和盐酸与硫化氢反应.过量的碘用硫代硫酸钠标准溶液滴定,以求出矿中S2-的含量.     

含氰贫液酸化产物中铜元素回收工艺研究

金精矿焙烧-氰化系统含氰贫液闭路循环需要定期开路部分贫液,贫液中的Cu元素具有一定的回收价值,本文在含氰贫液酸化法处理工艺基础上探索含氰贫液中Cu元素回收工艺的可行性。酸化处理后CN-挥发率为95.42%,铜沉淀率为97.82%。酸化后贫液固液分离所得酸化沉淀含铜22.77%～35.01%,采用焙烧-酸浸-萃取工艺回收铜,最佳实验条件如下：焙烧温度为640 ℃,液固比为5∶1,H2SO4质量浓度为5%,酸浸时间为3 h,此时可获得铜浸出率为92.27%～95.00%。以20%Lix984作为萃取剂,调节浸出液pH=2.3,有机相和水相相比为1∶1,萃取时间为3～5 min时,单级铜萃取率为98.96%;酸化后贫液固液分离所得液体平均铜浓度为72.89 mg/L,以硫化法深度沉淀铜,当Na2S用量为0.4～0.6 g/L,沉淀时间为1 h时,铜沉淀率为92.21%～99.09%。     

电位滴定法用于富锂锰基正极材料中钴的测定

钴含量的准确分析对控制富锂锰基正极材料电化学性能有重要意义。锰会对电位滴定测定钴产生干扰,而富锂锰基正极材料中锰含量较高,因此电位滴定测定钴时需要考虑锰的干扰。实验采用盐酸、硝酸溶解样品,加入氯酸钾将锰(II)氧化为二氧化锰沉淀并过滤分离。滤液中加入柠檬酸铵-氯化铵-氨水混合溶液及铁氰化钾标准溶液,使钴氧化完全,过量的铁氰化钾用钴标准滴定溶液进行电位滴定。二氧化锰沉淀连同滤纸用硫酸、硝酸硝化后,电感耦合等离子体原子发射光谱法(ICP-AES)测定沉淀中残留的钴。电位滴定法测定的钴量和沉淀中残留钴量的合量为样品中的钴含量。按照实验方法对1个富锂锰基正极材料实际样品和2个富锂锰基正极材料合成样品进行测定,测定结果的相对标准偏差(RSD,n=11)在0.26%~0.33%。采用实验方法对富锂锰基正极材料实际样品进行测定,并与ICP-AES进行对照试验,结果表明,两种方法的测定值相吻合。     

矿石中铅量测定方法的补正

采用国标法测定矿石中的铅量时,存在测定结果偏低或流程长、操作繁琐等问题,研究建立了矿石中铅量测定的补正方法。实验选择硝酸-氯酸钾溶液溶解试样,之后过滤分离,分别测定沉淀与滤液中铅量,二者加和即为矿石中铅量。该方法测定结果的相对标准偏差为0.06%~0.16%,加入标准物质回收率为98.25%~103.00%,提高了未知矿样测定的准确度,且操作简单,流程短。     

碘酸钾-淀粉光度法测定水样中生化需氧量(BOD_5)

生化需氧量(BOD)是环境监测中反映水质好坏的重要参数,本文依据碘酸钾为基准,提出了碘酸钾-淀粉光度测定水样中BOD5的新方法。实验以碘酸钾与过量碘化钾生成单质碘,新生成的单质碘与淀粉生成的蓝色物质在574 nm处有最大吸收,采用光度法测定5天前后培养水样中溶解氧的含量来计算水样中BOD5。所拟方法用于BOD5标准样品溶液、葡萄糖-谷氨酸标准溶液和污水厂进出口水样中BOD5的测定,结果与国家标准方法所得结果相一致。     

硫化钐中硫和钐的分离与测定

研究了一种可同时测定硫化钐中硫和钐含量的方法。硫化钐样品经氢氧化钠、过氧化钠熔融,将负二价硫全部氧化为正六价,经两次氨水分离,滤液在pH值为2~5的条件下,煮沸加入氯化钡溶液沉淀硫酸根,计算硫含量;氨水分离两次后的氢氧化钐沉淀经盐酸酸化后,用EDTA标准溶液滴定,测定钐含量。通过正交实验确定了熔样条件为550 ℃熔融10 min,氯化钡溶液沉淀硫酸根时沉淀不需陈化;由方差分析得出氨水分离次数和沉淀pH值为影响实验结果的显著因素,进一步试验确定氨水分离次数为2次、沉淀时pH值为2~5;此外,通过实验证明方法采用镍坩埚熔样所引入的镍并不影响测定结果。按实验方法对硫化钐样品进行精密度考察,硫和钐测定结果的相对标准偏差(RSD)分别为0.73%、0.18%;加标回收试验表明,硫和钐的回收率分别在101%~103%、100%~102%之间。采用实验方法对两个硫化钐样品进行测定,并分别与氯化钡滴定法测定硫及草酸盐重量法测定钐的结果进行对照,吻合较好。实验方法相比单元素测定法,避免了重复熔样,减少了样品预处理过程,实现了硫和钐的联合测定,可用于日常生产分析。     

间接原子吸收法测定铁合金中的磷

间接原子吸收法测定磷已有报导.本文研究了含过量钼酸铵的酸性溶液中,加入二安替比林甲烷(DAM),将试样中的磷转变为二安替比林甲烷磷钼酸沉淀,不经过滤分离,直接以空气一乙炔焰原子吸收法测定澄清液中未反应的剩余钼,间接计算磷含量.试验确定了沉淀条件,探讨了共存元素的干扰及其消除.所拟定的方法用于铁合金中磷的测定.结果满意.一、仪器与主要试剂WFX-1B型原子吸收分光光度计;LZ_(3-100)型函数记录仪; 电热恒温水浴.     

环境水样中生化需氧量的光度法测定研究

对传统的生化需氧量（BOD）测定方法进行了改进,采用I3- 结晶紫 聚乙烯醇体系光度法测定样品培养前后的溶解氧浓度,实验以碘酸钾与过量碘化钾生成单质碘,新生成的I3-与结晶紫生成的离子缔合物在550 nm 处有最大吸收,采用光度法测定5 天前后培养水样中溶解氧的含量来计算水样中BOD5。所拟方法用于BOD5标准样品溶液、葡萄糖 谷氨酸标准溶液和污水厂进出口水样中BOD5的测定,结果与国家标准方法所得结果一致。     

Thermochemical decomposition of hydrogen sulfide with nickel sulfide

In this research, the two-step thermochemical cycle shown below is proposed and experimental studies were made on the cycle. $$\frac{\begin{gathered} {\text{Ni}}_{\text{3}} {\text{S}}_{\text{2}} + {\text{H}}_{\text{2}} {\text{S}} = {\text{3NiS + H}}_{\text{2}} \hfill \\ {\text{3NiS = Ni}}_{\text{3}} {\text{S}}_{\text{2}} {\text{ + 0}}{\text{.5S}}_{\text{2}} {\text{(g)}} \hfill \\ \end{gathered} }{{{\text{H}}_{\text{2}} {\text{S = H}}_{\text{2}} {\text{ + 0}}{\text{.5S}}_{\text{2}} {\text{(g)}}}}$$ In the case where Ni₃S₂ alone was used without inert additions, nickel sulfide sintered or partly fused due to the melting point depression resulting from the thermal decomposition of formed NiS. Such sintering could be prevented by mixing the nickel sulfide powders with Al₂O₃ or MoS₂. The cyclic reactions were thereby shown to provide a stationary high decomposition rate of H₂S. Polysulfides, such as MS₂, have previously been employed in this kind of cycle. This research showed that the use of lower sulfides such as Ni₃S₂ may be regarded as rather promising based on the thermodynamic investigation of the respective reactions composing the cycle. The comparison between the sulfurization reactions of NiS to NiS₂ and of Ni₃S₂ to NiS further showed that the latter was superior to the former with respect to the kinetics and thermodynamical properties of the reaction.     

Evaporation of tantalum sulfide

Conclusions An investigation based on mass spectrometric, chemical, and x-ray diffraction techniques established that the tantalum sulfide TaS_2.00–1.38 is a variable-composition phase. Under the conditions of vacuum heating, the limiting composition of this phase is TaS_1.38.Translated from Poroshkovaya Metallurgiya, No. 5 (101), pp. 49–52, May, 1971.     

Oxidation of nickel sulfide

The oxidation of nickel sulfide whose atomic fraction of sulfur,x _s, is 0.40 to 0.44 was studied in a mixed O₂-N₂ gas stream at 923, 973, and 1023 K. The oxygen partial pressure was maintained at 2.0 x 10⁴ Pa. In the oxidation of nickel sulfide ofx _s = 0.40 and 0.41, a dense NiO layer was formed on the sulfide surface without the evolution of SO₂ gas, because of the low sulfur activity. Diffusion of nickel within the inner sulfide core toward the surface controlled the oxidation rate during the first one minute of oxidation. Subsequently, the oxidation rate was controlled by the diffusion of nickel through the formed NiO layer. In the oxidation of nickel sulfide ofx _s = 0.44 at 973 and 1023 K, the reaction proceeded irregularly to the interior of the sulfide core with the evolution of SO₂ gas, and a porous oxide layer was formed, due to the high sulfur activity of nickel sulfide. For the same reason, this oxidation was also accompanied by the dissociation of nickel sulfide. Under the experimental conditions ofx _s = 0.42, 1023 K and x_s = 0.44,923 K, the oxidation started with weight increase and without the evolution of SO₂ gas, and in the subsequent stage the weight decreased and SO₂ gas was evolved. K. HAJIKA, former Graduate Student     

Oxidation of cobalt sulfide

Dense plate of cobalt sulfide was oxidized in a mixed O₂-N₂ gas stream at 873 to 1123 K. Atomic fraction of sulfur of the sulfide was between 0.505 and 0.525, and the partial pressure of oxygen in the gas stream was varied between 5.05 x 10₃ and 2.02 x 10₄ Pa. At lower temperature, cobalt diffused from the interior of sulfide to the surface due to the lower sulfur activity, and a dense oxide layer was formed without the evolution of SO₂ gas. The oxidation rate was controlled by the diffusion of cobalt in the sulfide in the initial few minutes, and it was controlled by the diffusion of cobalt through the oxide layer in the subsequent oxidation. At higher temperature, the oxidation of cobalt sulfide proceeded accompanying the evolution of SO₂ gas due to the higher sulfur activity, and a porous oxide was formed. The oxidation rate was determined by the mass transfer of oxygen through the gas boundary film and the oxide layer.     

Oxidation of dense iron sulfide

Oxidation of stoichiometric iron sulfide was investigated. Rectangular plates of dense FeS were oxidized in an Ar-O₂ gas mixture at 1023 to 1123 K. Oxygen partial pressure was varied between 1.01 × 10³ and 2.03 × 10⁴ Pa. During the initial five minutes of oxidation, a magnetite layer of about 10 μm in thickness was formed on the surface without the evolution of SO₂ gas. Diffusion of iron from the interior of the sulfide to the sulfide/magnetite interface controlled the oxidation rate. Mass transfer through the gaseous boundary layer at the sample surface also affects the oxidation rate at lower oxygen partial pressures. Following this rapid formation of magnetite, the magnetite layer continued to grow for several hours in accordance with the parabolic rate law. Diffusion of iron through the magnetite layer controlled the oxidation rate during this stage. A thin layer of hematite was also formed on the outer surface of magnetite. When the composition of the inner sulfide core reached Fe_0.9S, the oxidation proceeded irregularly into the interior of the remaining sulfide. Porous oxide was formed and SO₂ gas was evolved. Former Graduate Student     

次生硫化铜矿微生物浸出实验

微生物浸矿是提取低品位,难选次生硫化铜矿中有价元素的最有效方法之一.本研究利用嗜酸氧化亚铁硫杆菌(Acidthiobacillus ferrooxidans)浸取福建某难选次生硫化铜矿,依次开展浸矿菌富集培养实验、驯化转代实验和不同粒径配比下柱浸试验,获得了不同阶段的细菌浓度、pH值、铜浸出率等演变规律;并结合电子计算机断层扫描技术实现了柱内矿堆塌落、截面孔隙演化和浸矿机理研究.研究表明:细菌浓度和pH值均呈现缓慢增加后趋降低的趋势,浸柱中细菌增殖较慢,浸矿480 h后,细菌浓度仅为每毫升5×107个.浸矿过程中,细颗粒趋于向柱底迁移,矿堆出现塌落;柱顶孔隙率变大,增幅为6.65%,柱底孔隙率变小,降幅为8.29%;塌落程度与细粒含量成正比,最小塌落为1.7 mm,最大塌落为6.15 mm.入堆矿石粒径极大影响着柱浸体系的浸出效果.实验中柱浸B组(粒径r < 1 mm占28.41%)浸矿效果最佳,浸矿480 h后铜浸出率达47.23%.      

Oxidation of mixed copper-iron sulfide

. A rectangular plate of mixed copper-iron sulfide composed of bornite (Cu₅FeS₄) and troilite (FeS) was oxidized in an O₂-Ar mixed gas stream at 1023 to 1123 K. At the start of the oxidation, iron was preferentially oxidized with the rapid formation of a dense Fe₃O₄ layer of about 10 μm thickness on the sample surface, without the evolution of SO₂ gas. Following this reaction, layers of both Fe₃O₄ and Fe₂O₃ grew on the sulfide surface in accordance with the parabolic rate law. The diffusion of iron through the oxide layers was assumed to control the oxidation rate during this stage. The effect of oxygen partial pressure on the parabolic rate constants was minor and an apparent activation energy of 126 kJ/mol was obtained. During the later stages of the reaction, when the sulfur activity in the inner sulfide core increased, the oxidation proceeded irregularly to the interior of the remaining sulfide with the formation of a porous oxide and the evolution of gaseous SO2. The remaining sulfide core was found to be a mixture of bornite (Cu₅FeS₄) and djurleite (Cu_1.96S). H. TSUKADA, former Graduate Student at Kyoto University     

Pelletizing of sulfide molybdenite concentrates

The results of a pelletizing investigation using various binding components (water, syrup, sulfite-alcohol distillery grains, and bentonite) of the flotation sulfide molybdenite concentrate (～84% MoS₂) from the Mongolian deposit are discussed. The use of syrup provides rather high-strength pellets (>3 N/pellet or >300 g/pellet) of the required size (2–3 mm) for the consumption of 1 kg binder per 100 kg concentrate. The main advantage of the use of syrup instead of bentonite is that the molybdenum cinder produced by oxidizing roasting of raw ore materials is not impoverished due to complete burning out of the syrup. This fact exerts a positive effect on the subsequent hydrometallurgical process, decreasing molybdenum losses related to dump cakes.