硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径

研究硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径。结果表明,间接作用机制和接触作用机制均对硫铜钴矿生物浸出过程产生影响。当细菌吸附到矿物表面时,矿物溶解速率显著加快,说明浸出过程中接触作用机制对硫铜钴矿的溶解有重要影响。浸出过程中硫元素氧化价态的变化顺序为S?2→S0→S+4→S+6,并有单质硫沉淀在矿物表面,说明硫铜钴矿生物浸出过程按照多硫化物途径进行。硫铜钴矿表面被细菌严重腐蚀,出现许多大小不一的腐蚀坑洞,并有单质硫、硫酸盐及亚硫酸盐生成。这些氧化产物在矿物表面形成一层钝化层。     

硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径（英文）

研究硫铜钴矿生物浸出过程中细菌的作用及其溶解反应途径。结果表明,间接作用机制和接触作用机制均对硫铜钴矿生物浸出过程产生影响。当细菌吸附到矿物表面时,矿物溶解速率显著加快,说明浸出过程中接触作用机制对硫铜钴矿的溶解有重要影响。浸出过程中硫元素氧化价态的变化顺序为S-2→S0→S+4→S+6,并有单质硫沉淀在矿物表面,说明硫铜钴矿生物浸出过程按照多硫化物途径进行。硫铜钴矿表面被细菌严重腐蚀,出现许多大小不一的腐蚀坑洞,并有单质硫、硫酸盐及亚硫酸盐生成。这些氧化产物在矿物表面形成一层钝化层。     

铝用阳极原料中的硫在生产过程中的迁移行为研究

随着石油焦中硫含量的增加,硫元素生产过程中转化为SO2所形成的环境污染日趋受到关注。本文以铝用阳极生产过程中的硫元素为研究对象,分析了原料、煅烧、焙烧及电解过程中硫元素在生产过程中的迁移行为。当煅烧温度加热到1330℃以上,稳定的噻吩结构中的硫碳键分解,脱硫效果迅速增加,硫元素生成SO2。焙烧温度为1100~1200℃时,在长时间高温状态下存在极少量的脱硫。硫元素在电解槽中初始会生成COS、CS2以及SO2等气体,大部分气体会被氧化成SO2气体。     

渗硫低碳钢焊接热裂纹产生机理与防治措施

1问题的提出 煤炭作为重要的能源物质，可以经过多种途径加工利用，包括气化、液化、焦化、热解、裂解等，但无论何种工艺，总会有硫化物生成，其中大约90％为H2S，还有少量CS2及硫醇。在化工生产中，硫的腐蚀主要指H2S腐蚀。某化工厂造气车间就是以煤炭为原料制取半水煤气，其组分为：CO＋CO2＋H2＋N2，其中H2含量37％，并含有一定量的H2S杂质，大约为0．5％；     

燃气中H2 S、C02气体腐蚀反应的化学热力学计算

运用化学热力学理论与计算方法对燃气中H2 S、CO2 与金属腐蚀反应的标准吉布斯函数、反应平衡常数、平衡分压等进行计算 ,从而得出腐蚀反应ΔG0 T关系式。通过这些数据 ,从理论上解释H2 S、CO2 对金属发生腐蚀反应的可能性 ,并进而推断出燃气中H2 S、CO2 对设备腐蚀的可能性大小和条件     

微米级硫钨酸铵在氢气中的分解过程

用DTA法和XRD法研究了粒度为63～75μm的硫钨酸铵在氢气中的分解过程,用Kissinger法、Freeman－Carroll法和Coast－Redfern法测得硫钨酸铵分解反应三个阶段的活化能分别为53．2,127．3和300．6kJ／mol,反应级数分别为0．8,0．6和1．5。硫钨酸铵在氢气中的热分解分四步进行,即（NH4）2WS4·H2O（s）→（NH4）2WS4（s）＋H2O（g）→WS2（s）＋2NH3（g）＋H2（g）＋2S（l）＋H2O（g）→WS2（s）＋2NH3（g）＋2H2S（g）＋H2O（g）→WS2（s）＋W（s）＋2NH3（g）＋2H2S（g）＋H2O（g）,分解开始温度为～150℃,分解终止温度为～380℃。     

燃气中H2S、CO2气体腐蚀反应的化学热力学计算

运用化学热力学理论与计算方法对燃气中H2S,CO2与金属腐蚀反应的标准吉布斯函数,反应平衡常数,平衡分压等进行计算,从而得出腐蚀反应ΔG^0-T关系式,通过这些数据,从理论上解释H2S,CO2对金属发生腐蚀反应的可能性,并进而推断出燃气中H2S,CO2对设备腐蚀的可能性大小和条件。     

在H_2SO_4-Fe_2(SO_4)_3体系中载金黄铁矿浸出动力学（英文）

在H2SO4-Fe2(SO4)3体系中研究载金黄铁矿的浸出动力学,探讨反应温度、Fe3+浓度、硫酸浓度、搅拌速度等对黄铁矿浸出的影响规律。结果表明:在H2SO4-Fe2(SO4)3体系中,在30~75°C下黄铁矿浸出过程主要受化学反应控制Fe3+浓度与黄铁矿的浸出呈正相关,通过Arrhenius经验公式求得浸出表观活化能为51.39 k J/mol。EDS与XPS分析结果表明:黄铁矿氧化过程中硫的氧化经一系列中间形态,最终被氧化成硫酸根,并伴有部分元素硫生成,符合硫代硫酸根氧化路径机理。     

N80抗硫油管钢在含CO2、微量H2S及高浓度Cl-腐蚀介质中的腐蚀行为

用失重法、扫描电镜（SEM）、X射线能谱(EDS)及X射线衍射能谱(XRD)对N80抗硫油管钢在CO2、微量H2S及高浓度Cl-条件下的腐蚀行为进行了研究.结果表明,在本实验条件下,腐蚀反应以H2S腐蚀为主;在膜的形成过程中FeS腐蚀产物膜优先形成,并进一步阻碍具有良好保护性的FeCO3腐蚀产物膜的形成;腐蚀产物膜疏松、平均腐蚀速率较大,且有轻度局部腐蚀发生;溶液中高浓度的Cl-及材料中高含量的Cr元素会使N80抗硫钢局部腐蚀倾向加大.     

含H2S/CO2环境中缓蚀剂对不同油管钢的缓蚀作用

选用一种自制缓蚀剂TG500(主要成分为咪唑啉含硫衍生物、有机硫代磷酸酯),对不同油管钢在含H2S/CO2腐蚀介质中进行试验。结果表明:TG500可明显降低溶液对N80、SM80SS、KO80SS油管钢的腐蚀速率,即使在较高的CO2/H2S分压下,缓蚀效率仍可达95%以上;油管钢中的合金元素Cr、Ni对于降低油管钢的腐蚀速率具有明显作用,但对于提高缓蚀剂的缓蚀效率无明显作用。     

Die Verzunderung von Eisen zwischen 700 und 900 °C in CO/CO2-Gemischen mit kleinen Zusätzen von COS,SO2 und H2S

Scaling of iron between 700 and 900°C in CO/CO₂mixtures with minor additions of COS, SO₂ and H₂S Scaling of iron in CO/CO, mixtures containing less than 1.6% COS, H₂S or SO₂follows initially a linear kinetic law. The transition from the linear to the parabolic law is displaced toward shorter periods with increasing sulfur contents in the gas and with decreasing temperature. At 800 and 900°C the rate of the reaction between iron and the sul-fur compound in the gas is controlled by the mass transfer in the gas phase. In this conditions the reaction rates with COS and H₂S are practically identical, while the reaction with SO₂yields al-most double the weight increase because in this case not only sulfur, but also part of the oxygen of SO₂ react with iron. At 700°C there is a transition of the control mechanism in CO/CO₂C/S mixtures with increasing COS contents, namely from control by mass transfer in the gas phase to control by the phase boundary reaction. Some consequences concerning the heating of steel in technical furnaces are discussed.     

Metallographische Untersuchungen über den Aufbau des Zunders nach Oxydation von Eisen zwischen 700 und 900 °C in CO/CO2-Gemischen mit kleinen Gehalten an COS,H2S oder SO2

Metallographic investigations into the structure of the scale after oxidation of iron between 700 and 900°C in CO/Co₂ mixtures with minor additions of COS, H₂S or SO₂ The results of metallographic investigations are in agreement with kinetic measurements published recently (Werkstoffe u. Korrosion 21 [1970] 925) and with analytical investigations of the scale. When because of the CO/CO₂ ratio only a reaction with the sulfur compound is possible, pure sulfide layers are formed in gases containing COS and H. S. When, however, in addition to the reaction with the sulfur compound. A reaction with CO₂ is feasible, an inti-mate mixture of FeO and FeS is formed according to a linear scaling law. When the scale is high in oxide, the FeS particles are embedded in linear shape in a FeO matrix. When the scale has medium contents of oxides and sulfides a perlitic structure is formed consisting of FeO and FeS lamellae in parallel arrangement, the location changing from one grain to the other. With the transition to a parabolic law, i.e. with the transition to rate controlling diffusion of iron ions and electrons through the scale layer, only thermodynamically stable FeS is formed. Under certain conditions needles, predominantly of pure FeS, grow out from the compact scale layer. These needles have diameters between 5 and 20 lm, and may attain lengths up to 600 pn. With the transition to the parabolic law they probably grow in thickness and finally form a coherent FeS layer. In CO/CO₂ mixtures containing SO₂ essentially the same structures are formed, in this context it must be noted, that SO₂ may supply not only sulfur but also oxygen. This is why such FeO/FeS lamellae are formed in such gas mixtures where CO₂, cannot supply oxygen. Higher SO₂ and CO₂, contents in the gas the FeO/FeS lamellae “degenerate” form a coarser mixture of sulfide and oxide.     

The application of gas phase and solid state X-ray photoelectron spectroscopy to the investigation of derivatives containing the repeating SN unit

Solid state X-ray photoelectron spectra of S₂N₂, S₄N₄, (SNBr_0.04)_x, and (SNBr_0.25)_x have been obtained and the gas phase spectrum of S₂N₂ is also reported. Both the solid state and gas phase core level spectra, as well as MNDO and CHELEQ calculations, show that there is greater S → N charge transfer in S₄N₄ than in S₂N₂. The solid state data indicate that the charge distributions in S₂N₂ and (SN)_x are the same. All of the data can be satisfactorily explained without recourse to N pπ → S dπ bonding. Bromination of an (SN)_x film and single crystals results in complicated, broad N 1s and S 2p envelopes. Changes in the relative core level intensities on bromination suggest that the bromine resides largely between and/or on the (SN)_x fibrils, rather than penetrating into the fibrils.     

pH-dependent leaching mechanism of carbonatitic chalcopyrite in ferric sulfate solution

The dissolution of a carbonatitic chalcopyrite (CuFeS₂) was studied in H₂SO₄−Fe₂(SO₄)₃−FeSO₄−H₂O at varying pH values (0.5−2.5) and 25 °C for 12 h. Experiments were conducted with a size fraction of 53−75 µm. Low Cu recoveries, below 15%, were observed in all pH regimes. The results from the XRD, SEM−EDS, and optical microscopic (OM) analyses of the residues indicated that the dissolution proceeded through the formation of transient phases. Cu_3.39Fe_0.61S₄ and Cu₂S were the intermediate phases at pH 0.5 and 1.0, respectively, whereas Cu₅FeS₄ was the major mineral at pH 1.5 and 1.8. The thermodynamic modelling predicted the sequential formation of CuFeS₂→ Cu₅FeS₄→Cu₂S→CuS. The soluble intermediates were Cu₅FeS₄ and Cu₂S, whilst, CuS and Cu_3.39Fe_0.61S₄ were the refractory phases, supporting their cumulating behaviour throughout the dissolution. The obtained results suggest that the formation of CuS and Cu_3.39Fe_0.61S₄ could contribute to the passive film formed during CuFeS₂ leaching.     

The Role of Cu(I) in the Process of Forming Cu2–xS Coatings by a Chemical Route

The interaction of the Cu₂O adsorbed with Na₂S_n (n = 1–4), during formation of the Cu_2–xS coatings has been investigated by cyclic voltammetry.

The summarized reaction of this process has been shown to correspond to the equation:

Na₂S_n + Cu₂O_ad + H₂0 → Cu₂S_ad + (n–1)S^o + 2NaOH,

where S^o/Cu=(n–1)/2. Such a stoichiometry of reaction can be explained by the formation of an intermediate—the adsorbed polysulphide of Cu(I)—and by its subsequent decomposition into Cu₂S and S^o.

When a thicker coating is being formed, i.e., when the surface being coated is repeatedly immersed into an ammoniate solution of Cu(I) and S^o fully bounded:

S^o_ad + 2 Cu⁺ → CuS + Cu²⁺.

At the same time due to different solubility products (L=2.5·10^?48 and 6.3·10^?36 for Cu₂S and CuS respectively), an exchange

CuS_ad + 2(1–x)Cu⁺ → Cu_2–xS_ad+ (1–x)Cu²+ occurs.

After formation of Cu²⁺, parallel processes characteristic for the interaction of Cu(II) with Na₂S_n start to take place, during which S^o is also formed.     

Equilibria in the gas system S-O-C between 550 and 1100°C

Equilibria in the S-O-C gas system have been calculated, for a variety of starting values of CO, CO₂, and SO₂ between 550–1100° C, assuming the existence of 10 gaseous species. It is shown that the species COS, SO₃, CS, and SO may form in concentrations sufficiently high that values of sulfur and oxygen partial pressures, calculated from the initial values of CO, CO₂, and SO₂, are in error. Results are given for three sets of initial compositions and are available for 39 more.     

Mesoscale Evaluation of Titanium Silicide Monolayer as a Cathode Host Material in Lithium–Sulfur Batteries

Two-dimensional materials are competitive candidates as cathode materials in lithium–sulfur batteries for immobilizing soluble polysulfides and mitigating the shuttle effect. In this study, a mesoscale modeling approach, which combines first-principles simulation and kinetic Monte Carlo simulation, is employed to evaluate titanium silicide (Ti₂Si and TiSi₂) monolayers as potential host materials in lithium–sulfur batteries. It is found that the Ti₂Si monolayer has much stronger affinities to Li₂S _x (x = 1, 2, 4) molecules than does the TiSi₂ monolayer. Also, Ti₂Si can facilitate the dissociation of long-chain Li₂S₄ to LiS₂. On the other hand, TiSi₂ can only provide a weak chemical interaction for trapping soluble Li₂S₄. Therefore, the Ti₂Si monolayer can be considered to be the next-generation cathode material for lithium–sulfur batteries. Nevertheless, the strong interaction between Ti₂Si and Li₂S also causes fast surface passivation. How to control the Li₂S precipitation on Ti₂Si should be answered by future studies.     

Investigation of the Interaction Between Cu2-x S +So Coatings and Pd(II) Ions by Cyclic Voltammetry and X-ray Photoelectron Spectroscopy

The interaction between Pd²⁺ ions and Cu_2-xS coating formed by three cycles and containing ~30 at.% of elementary S has been investigated by the methods of cyclic voltammetry and photoelectron spectroscopy (one cycle of coating formation includes treatment of the surface with Cu(I)+Cu(II) ammoniate solution, hydrolysis of the adsorbed copper compounds and sulphidation of copper oxygen compounds in Na₂S_n solution). After exposure of such a coating to Pd²⁺ ions (1.7 mM PdCl_2’ pH-2), an exchange as well as a redox interaction between the coating components and Pd²⁺ ions has been shown to occur. Due to this the amount of copper in the coating decreases from 2 to 4 times and that of sulphur from 1.5 to 5 times. The coating modified in such a way has been found to contain up to 75 at.% of palladium, ~90% of it being in a metallic state.

It has been determined that at the beginning S^o is bound into a soluble compound:

2Pd²⁺ + S^o + 3H₂O → 2Pd^o + H₂SO₃ + 4H⁺.

The Cu₂S present in the coating is considered to interact with Pd²⁺, with the formation of Pd⁰ and CuPdS_2’, while CuS reacts most likely according to the reaction:

CuS + 3Pd²⁺ + 3H₂O → 3Pd^o; + H₂SO₃ + Cu²⁺ + 4H⁺.

The Cu_2-xS +S^o coating formed on a dielectric and modified with Pd²⁺, contrary to the initial Cu_2-xS +S^o coating, can be plated with copper from any electrolyte for copper deposition.     

The corrosion of copper by atmospheric sulphurous gases

The sulfurization of copper by atmospheric gases is widely recognized, but the importance of the potential causative agents of sulfurization and the mechanisms involved have remained unresolved. In this work, polycrystalline copper has been exposed to the atmospheric gases hydrogen sulfide (H₂S), carbonyl sulfide (OCS), carbon disulfide (CS₂), and sulfur dioxide (SO₂) in humidified air under carefully controlled laboratory conditions. At room temperature, the rates of sulfurization by H₂S and OCS are comparable, and are some two orders of magnitude greater than those by CS₂ and SO₂. Given the atmospheric concentrations of these gases, it is clear that OCS is the principal cause of atmospheric sulfurization of copper except near sources of the gases where high concentrations may render H₂S (and possibly SO₂) important. At constant absolute humidity, the sulfurization rate of copper by OCS is found to be inversely proportional to temperature over the range 21–80°C, a property attributed to reduced quantities of surface water at high temperatures and the subsequent decrease in the rate of hydrolytic transformation of OCS into a reactive form. In a final series of experiments, the initial sulfurization of copper by 2.2 ± 0.2 ppm H₂S in humidified air at 22°C has been studied in detail. The first stages of sulfurization involve rapid attack by H₂S at surface defect sites. As these corrosive mounds spread and merge, diffusion of copper to the surface is impeded and the fraction of H₂S molecules striking the surface that become incorporated into the corrosion film drops sharply from ～ 5 × 10^?5 (at t = 5 s) to ～ 8 × 10^?7 (at t = 72 h).     

Kinetic conditions for the simultaneous formation of oxide and sulphide in reactions of iron with gases containing sulphur and oxygen or their compounds

The scaling of pure iron has been investigated in N₂O₂SO₂ and COCO₂COS mixtures between 700 and 900°C. Simultaneous formation of FeO and FeS at the scale/gas phase boundary is observed when the diffusion in the aerodynamic boundary layer or the reaction at the scale/gas phase boundary is the rate-controlling step of the oxidation in O₂N₂ mixtures or of the sulphidation in COCOS mixtures. In those cases the addition of the second oxidant (SO₂ to O₂N₂ mixtures, and an increased CO₂ to COCO₂COS mixtures) increases the rate of the oxidation or sulphidation reactions. When, however, the diffusion of iron ions and electrons through the oxide or sulphide layer respectively, or the reaction at the metal/scale phase boundary are rate-determining, the thermodynamically stable phase (oxide or sulphide) is formed exclusively and the addition of the second oxidant has no influence on the scaling rate. These results may be understood from an evaluation of the equilibria prevailing at the scale/gas phase boundary.