Investigations of Sulfuric Acid Corrosion of Concrete. II: Electrochemical and Visual Observations

Degradation of a mortar specimen exposed to an acidic sulfate solution was studied using iron pins set within the sample with their ends close to the surface. Electrochemical impedance spectroscopy and the open circuit potential of the pins were used to monitor corrosion behavior. An experiment in which the pH of the test solution was maintained in the range of 4–5 for 8 days and 2–3 for 73 days was performed. The experimental data were used to investigate the efficacy of a diffusion-reaction based model with a moving boundary for the corrosion process. The open circuit potential of the pins indicated initiation of active corrosion of the pins closest to the surface of the mortar after 36 days in the second experiment. Visual observation of the cross section of the mortar sample at the end of the experiment indicated that 0.82 mm of the mortar was corroded. The data established the validity of the moving boundary paradigm for sulfide corrosion of concrete. Electrochemical impedance spectroscopy and open circuit potential were found to be valuable tools for monitoring corrosion of the iron pins in the specimen.     

Modeling Water and Sulfuric Acid Transport through Coated Cement Concrete

The behavior of coated cement concrete in water and sulfuric acid was investigated over a three-year period. Two epoxy-based coatings were selected and cylindrical concrete specimens were coated and used in this investigation. The concrete-to-coating mass transfer coefficient ratio varied from 8 to 10. The penetration of liquids through bulk coating materials and coated concrete with and without holidays (pinholes) was studied. The mass change of the specimens was measured at regular intervals and a total of 64 coated specimens were tested. Coated concrete specimens with and without holidays had different performance with long-term immersion in deionized (DI) water and 3% sulfuric acid. Mass transfer models were developed using film and bulk concepts and were used to predict the increase in mass in coated concrete in nonreactive DI water and reactive 3% sulfuric acid solutions. The mass transfer model parameters for various solution-coating combinations were obtained from experiment data. The parameters of the effect of holiday size on the liquid transport process were also identified based on the experiment results.     

Titanium Containing High Strength Sulfuric Acid Corrosion Resistant Steel

Ti containing low alloy steel free of Sb is found to have higher strength than and equivalent sulfuric acid corrosion (SAC) resistance to traditional SAC resistant steels in Cu? Cr? Sb system. SAC resistance of the Ti containing steel was investigated with potentiodynamic polarization, linear polarization resistance, electrochemical impedance spectroscopy, and weight loss measurements in a solution of 20 wt% H₂SO₄ at 20°C. All measurements confirm that Ti addition is suitable for designing high strength SAC resistant steels.     

硫酸生产中泵的腐蚀与优化改进

在WSA硫酸生产中需要大量的泵，输送介质为含有大量氟、氯离子的稀硫酸，其腐蚀性极强，泵的过流部件经常被腐蚀掉，不能继续使用，需耗费大量的人力和物力，同时还影响系统的生产，通过对其腐蚀机理进行分析，对泵进行相应改进，降低设备故障率，从而节约大量费用，保证了系统生产的稳定。     

S-TEN3和CRIA系列钢的耐硫酸露点腐蚀性能

通过浸泡实验测出了S-TEN3、CRIA两类钢种在各种硫酸介质中的腐蚀速率。结果表明,Sb和Ti分别能显著改善S-TEN3和CRIA钢的耐硫酸露点腐蚀性能。在此基础上,探讨了合金元素在腐蚀过程中的作用。     

浸渣及烟尘中镉的物相分析

试验并制定了硫酸浸渣及烟尘中镉的物相分析方法，可以测定硫酸盐相、氧化物相、金属相、硫化物相和其它结合相（铁氧化物吸附相和硅酸盐矿物中类质同象相）。特别选用乙醇溶液浸取硫酸镉，降低了氧化镉的干扰。样品分析和回收实验结果满意。     

硫酸厂浓酸泄漏事故原因分析及应急处理方法

在对硫酸中金属腐蚀机理分析的基础上,探讨了硫酸厂浓酸区域各种泄漏情况产生的原因,并且针对不同的泄漏情况,提供了相应的应急处理方法。     

天钢抗硫酸露点腐蚀09CrCuSb圆钢的开发

介绍了天钢利用转炉—精炼—VD—方坯连铸—轧钢工艺生产抗硫酸露点腐蚀09CrCuSb圆钢的开发过程。通过精炼的强化脱氧、化学成分的精确控制、连铸二冷工艺的优化和轧钢工艺的精确温度控制,开发出了09CrCuSb圆钢并形成完整的生产工艺。经检测该产品完全符合相关标准,达到了设计要求。所生产的圆钢得到用户的好评。     

激光熔覆耐硫酸腐蚀 Ni 基合金组织及性能的研究

根据耐硫酸腐蚀阀门的性能要求,研发出了符合性能并适合激光熔覆的合金粉末。使用半导体激光在 304 不锈钢基体上熔覆耐高温浓硫酸腐蚀熔覆层。使用扫描电镜、EDS、XRD 对熔覆层的组织结构进行分析,熔覆层 内主要由 Ni_2.9Cr_0.7Fe_0.36、FeNi₃、Fe_0.64Ni_0.36、γ-(Fe,Ni)等物相组成。对熔覆层的显微硬度和洛氏硬度进行测定, 熔覆层的显微硬度范围在 HV0.2600 ~ HV0.21000 内,洛氏硬度约为 HRC63;熔覆层在 120°C,98% 浓硫酸中的腐 蚀速率为 0.0205mm?a^-1,耐腐腐蚀等级为 4 级,对熔覆层的耐腐蚀机理进行了分析。硬度及耐腐蚀性均达到硫酸 生产企业对耐硫酸腐蚀阀门的性能要求。在此基础上,在阀门样品上制备了耐腐蚀激光熔覆层样件,为工程应用 奠定了基础。     

耐硫酸露点腐蚀钢09CrCuSb氧化铁皮缺陷的分析与研究

针对耐硫酸露点腐蚀钢09Cr Cu Sb热轧时出现的表面氧化铁皮压入缺陷,通过EPMA进行表面、断面形貌分析,研究了形成原因及控制方法。结果表明:降低加热炉均热段温度、合理控制空燃比和刷漆可有效控制板材表面氧化铁皮压入缺陷。     

浅谈硫酸厂安全生产管理

针对硫酸生产中 ,安全与生产的矛盾关系 ,根据个别被硫酸烧伤现象等进行分析安全管理与生产之间的关系 ,一方面为硫酸生产提供安全保障 ,另一方面为企业安全管理与生产管理之间的相互关系提供论据     

烟气制酸一级动力波入口压力控制系统建模

介绍某冶炼厂烟气制酸净化过程各部分工艺及工作原理,并结合实际情况及控制目标设计了一级动力波入口压力控制系统,建立了各部分的机理模型。利用从现场采集的实际数据以最小二乘法辨识系统未知参数,并采用单元集成混合建模、分段近似线性化等方法得到主控制通道和干扰通道对象模型。利用现场数据验证了本模型的准确性和有效性。     

化选矿硫酸浸出稀土工艺研究

化选矿经硫酸浸出,在合适的酸度、温度、反应时间条件下,稀土浸出率为90%。     

烧结自制硫酸与工业硫酸酸洗不锈钢效果评定

以太钢产量较大的铁素体不锈钢430为试验原料,在实验室模拟现场酸洗工艺条件,采用烧结自制硫酸和现场用工业硫酸分别进行酸洗试验,对其性能进行了对比.试验表明,采用烧结自制硫酸酸洗喷丸后的430不锈钢比工业硫酸速率较慢,且试样颜色较白亮,但扫描电镜观察两种酸酸洗后试样的腐蚀形貌没有明显差异.     

硫磷混酸体系中钒的萃取实验研究

以某高磷钒矿直接活化硫酸浸出并经预净化的溶液作为研究对象,用N263进行萃取反萃后经过直接沉钒,制得V2O5产品.实验主要研究了水相平衡pH、萃取剂浓度、添加剂浓度、相比、逆流萃取及反萃级数对硫磷混酸体系中钒萃取率的影响.实验确定了N263最佳萃取工艺条件:有机相浓度取15%N263-5%仲辛醇-磺化煤油,O/A=1:3,常温振荡10 min,常温静置10 min,萃取平衡pH=2,经5级逆流萃取,钒的萃取率可达99.51%;最佳反萃工艺条件:反萃剂浓度取1 mol·L-1 NH4 OH4 mol·L-1 NaCl,O/A=3:1,常温振荡10 min,常温静置10 min,反萃平衡pH=8.5,经4级逆流反萃,钒的反萃率可达99.58%;经直接沉钒所得V2O5产品质量达到99.54%,符合GB3283-87V2O598质量要求.     

硫酸工业现状分析与发展规划思路探寻

在2016年十三五开局的过程中,硫酸工业在面临发展机遇的同时,也迎接着巨大的挑战,适应新常态、认识新常态以及规划发展是重点工作内容之一,相关管理人员必须要全面把握行业发展趋势,摸索出行业发展规律,促进硫酸工业的稳定进步。     

关于硫酸烧渣的利用及建议

通过对国外及我国目前制酸、炼铁行业的基本情况介绍，针对我国的实际情况提出在选太过程中应将硫精矿的品位提高到４６％以上，从而使制酸烧渣的ＴＦｅ含量大于６０％，以达到硫、铁双资源的利用；并且可以大大的改善环境条件。     

硫酸工艺计算软件的设计与实现

硫酸工艺设计计算存在参数多、计算量大的特点。采用计算机编程技术编制硫酸工艺设计计算软件,为硫酸工艺设计时大量的计算提供电子化服务,以方便快捷的计算机计算代替了传统的手工计算,充分发挥了计算机技术的优势,把人从繁杂和重复的计算劳动中解放出来,有效地降低设计成本,大幅减少了设计周期,提高了工作效率。     

Dynamics of Large Polymictic Lake. I: Field Observations

The internal dynamics of Clear Lake, California—a large, multibasin and polymictic lake—under stratified conditions is described in this work. Particular attention is paid to one of the subbasins of Clear Lake (Oaks Arm). Several field experiments were conducted in the lake to obtain data of wind, currents, and water temperature using a wide range of devices. Based on field observations and previously published results on basin responses to wind stress, a conceptual model of the internal circulation of the Oaks Arm is proposed. Its internal dynamics are characterized by diurnal cycles of setup and relaxation of horizontal temperature gradients driven by the wind forcing. The setup and relaxation processes are modulated by the influence of the earth’s rotation and create a residual cyclonic circulation. This circulation mechanism is here referred to as baroclinic pumping. It is in all likelihood not exclusive to Clear Lake but probably exists in other large and relatively shallow lakes forced by strong and almost periodic wind events where basin-scale internal waves do not play a major role in the dynamics of the system.