Extraction of valuable metals from Ti-bearing blast furnace slag using ammonium sulfate pressurized pyrolysis−acid leaching processes

A novel method of extracting valuable metals from Ti-bearing blast furnace slag(TBBF slag)via pressure pyrolysis of recyclable ammonium sulfate(AS)−acid leaching process was proposed.The results show that when pressurized roasting at an AS-to-slag mass ratio 3:1 and 370℃for 90 min,the extraction rates of titanium,aluminum and magnesium reached 94.5%,91.9%and 97.4%,respectively.The acid leaching solution was subjected to re-crystallization in a boiling state to obtain a titanium product having a TiO2 content of 94.1%.The above crystallization mother liquor was adjusted to pH=6 and pH≥12.2,respectively,and then qualified Al2O3 and MgO products were obtained.The analysis through XRD and SEM−EDS proves that the main phases in roasted samples were NH4AlSO4,CaSO4 and TiOSO4.The thermodynamic analysis presents that the main minerals of perovskite,spinel and diopside in raw ore could spontaneously react with the intermediate produced by AS under optimal conditions.

Recovery of zinc from electric arc furnace dust by alkaline pressure leaching using iron as a reductant

To recover zinc from electric arc furnace(EAF)dust,a process of primary normal pressure leaching and secondary alkaline pressure leaching is proposed.First,under the alkaline pressure leaching system,the experiment of pure zinc ferrite being reduced by iron powder was carried out.Under the optimal reduction conditions(i.e.,temperature of 260℃,NaOH concentration of 6 mol/L,liquid-to-solid ratio of 50 mL/g,and a 5-fold excess of iron powder),89%of zinc was extracted.The iron in the reduced residue exists as a magnetite phase.Subsequently,the normal pressure leaching experiment was carried out with EAF dust as raw material,and 66%zinc was leached.The main phase of zinc in normal leaching residue was determined to be zinc ferrite.Then,the normal leaching residue was reduced by iron powder under the alkaline pressure leaching system,and 66.5%of zinc was extracted.After the two-stage leaching process,the leaching rate of zinc in EAF dust can achieve 88.7%.The alkaline pressure leaching solution can be returned as the normal pressure leaching solution,and the magnetite in the alkaline pressure leaching residue can be recovered by magnetic separation.

Flexible Furnace Concepts for Vacuum Heat Treatment Combined with High-pressure Gas Quenching

IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.

Based on the experimentation mathematical modeling and autoregulation realization for gas-collector pressure of coke furnace

Technical process and pressure control system of coke furnace were introduced.The mathematical model based on experimental method of gas-collector pressure wasproposed.To a certain extent, it is more reliable and dependable than mechanism method.Manufacturing process and experimental modeling can be finished at the same time, andfurthermore, the mathematical model can be established automatically.The realization algorithmof the total decoupling and on the line's modification for model value plays an importantrole in improving regulating quality.Finally, the DCS network structure to realizethe process was introduced.The control results show that the regulator can get reliableand robust performance.

Study on co-cracking performance of different hydrocarbon mixture in a steam pyrolysis furnace

Co-cracking is a process where the mixtures of different hydrocarbon feedstocks are cracked in a steam pyrolysis furnace, and widely adopted in chemical industries. In this work, the simulations of the co-cracking of ethane and propane, and LPG and naphtha mixtures have been conducted, and the software packages of COILSIM1 D and Sim CO are used to account for the cracking process in a tube reactor. The effects of the mixing ratio, coil outlet temperature, and pressure on cracking performance have been discussed in detail. The co-cracking of ethane and propane mixture leads to a lower profitability than the cracking of single ethane or single propane. For naphtha, cracking with LPG leads to a higher profitability than single cracking of naphtha, and more LPG can produce a higher profitability.

Oxidation of Fe-Cr-Ni Alloys in a Low Oxygen Partial Pressure Atmosphere to Mitigate Coke Formation

Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed by energydispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-cokingperformance of a mini tube made of a HP40 (25Cr35Ni) alloy was evaluated on a bench scale pyrolysis and coking test unit.The results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partialpressure atmosphere. The oxide films were mainly composed of MnCr_(2)O_(4) and Cr_(2)O_(3). The average mass of coke in the minitube with oxide film decreased by 87% relative to that of a tube without an oxide film when the cracking temperature was 900℃. The ethylene, propylene, and butadiene yields in the pyrolysis tests were almost the same for the mini tubes withand without an oxide film. The oxide film on the alloy surface effectively inhibited catalytic filamentous coke formation.An industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantlyextended.

循环流化床锅炉节能减碳运行调控及工程验证

构建基于烟气中氧气体积分数及炉膛出口压力的锅炉运行协同控制模型,可以实时、准确地预测烟气中氧气体积分数的变化趋势,提前给定锅炉二次风机和引风机控制指令,显著减小了不同负荷条件下锅炉烟气中氧气体积分数、负压等关键运行参数的波动.在300 t/h循环流化床锅炉上的工业验证结果表明:利用协同控制模型可以提高锅炉运行控制的品质,锅炉变负荷工况条件下烟气中氧气体积分数控制在目标值±0.25%范围内,炉膛出口压力控制在目标值±45 Pa范围内的统计概率为99%.运行一周的统计结果表明,相比于原有控制,协同控制模型投运后单位产汽量耗煤可以减小1.508%,单位产汽量风机耗电可以减少1.886%.

高炉放散煤气治理技术

总结了高炉均压放散煤气和休风放散煤气治理技术的研究进展和应用情况。高炉均压放散煤气干法回收技术自2014年起逐步在京津冀地区率先获得推广应用至今,经过多次迭代更新,最终形成了“三级除尘+高效引射+智能控制”的引射法均压煤气干法全回收技术,该技术成熟可靠,已在国内多数高炉上获得成功应用。对于高炉休风放散煤气治理技术的研究仍处于发展阶段,当前的主流技术路线是利用现有煤气净化设施,通过在调压阀组区域并联引射器,对高炉休风末期、炉顶放散阀开启前的炉内低压煤气强制回收进入管网,可实现休风煤气全量回收,达到应收尽收,在休风结束时,高炉炉顶放散阀开启前,炉顶压力可降至0~1 kPa。但该技术仅适用于长期休风和短期休风,不适用于降料线休风和事故紧急休风。鉴于高炉休风过程的煤气回收操作是一项危险性作业,对休风放散煤气的治理还需在确保安全的前提下谨慎选择。选择技术方案时,需要综合考虑节能环保、投资、运行维护成本对高炉生产的影响以及系统是否能安全可靠运行等多方面的因素,采用性价比高的技术实现钢铁企业的长期绿色发展。

首钢股份高炉喷吹生物质微粉的可行性分析

对首钢股份高炉喷吹生物质微粉的可行性进行了分析。结果表明:①河北省唐山市一年的生物质微粉产量折合约137.64万t,可满足高炉喷吹的燃料需求,生物质资源的使用成本约为877.4元/t,用于高炉喷吹具有较好的经济效益;②几种利用变压闪蒸技术制备的生物质微粉样品中,样品7最适合进行高炉喷吹,其灰分低、水分低,能量密度接近褐煤水平,但后续仍需对工艺参数进行不断优化,以提高品质;③基于1号高炉的生产参数及原燃料质量,用31.6kg/t的样品7替代10kg/t煤粉较为可行,风口热状态相较于基准工况变化较小。

浸没式多孔道喷枪气体流动与传热特性数值模拟研究

喷枪作为熔池熔炼过程的关键设备,其性能直接影响气流对熔体搅拌效果。本文以阳极泥侧吹炉所使用的浸没式多孔道喷枪为研究对象,建立了长度约为800 mm的多孔道喷枪流动传热物理模型,基于SST k-ω湍流模型对喷枪内的气体流动与传热过程进行了数值模拟研究,分析了喷枪内气流温度、流速以及压力的分布特征,研究了天然气与富氧空气在不同流量下的气流压力沿流动方向变化特性、流量与出口流速间的关系以及流量对喷枪的冷却效果。结果表明,喷枪的多孔道结构有利于提高气体出口流速,强化气流对喷枪的冷却作用;然而,气流在孔道截面突变处以及出口段存在较大压力损失,不利于提高喷枪出口气体流速;随着气体流量的增大,喷枪出口流速显著增大,天然气与富氧空气在喷枪出口段的压力损失分别达到其入口总压的40%和25%;此外,流量对喷枪的冷却效果明显,天然气与富氧空气每增大5 Nm^(3)·h^(-1)、10 Nm^(3)·h^(-1),喷枪出口段温度下降约15 K。

基于Fluent的ALD型压力烧结炉温度场的优化模拟

利用ANSYS FLUENT对压力烧结炉内的温度场进行仿真模拟,分析了高温段(炉温1450℃)真空条件下炉内温度的分布状况,发现炉内温度分布不均匀,批次温差达16℃,且炉门处制品的温度偏差最大。分析认为加热体的形状和分布对温度场均匀性的影响最大,为了优化炉内温度分布,提出了增大炉门处加热体的尺寸、在炉门处增设环状或棒状加热体等三种改进方案。研究结果表明:在改变加热体的数量、结构及分布后,三种优化方案的炉内制品批次温差分别下降4.6、3.2℃和2.8℃,其中以增大炉门处加热棒尺寸的优化效果最佳。不仅显著降低了炉门处制品的温差,同时也提升了装料区制品温度的均匀性,为提高烧结产品的质量提供保障。

气相色谱法测定异戊烷中微量CO、CO_(2)的研究

利用高压液体进样阀-气相色谱仪,结合镍转化炉,建立了一种测定异戊烷中微量CO和CO_(2)含量的分析方法,考察了方法的精密度、回收率以及最低检测限,并对实际异戊烷样品中CO、CO_(2)的含量进行分析。定量分析结果表明,标样组分的回收率为98.0%,重复3次测定的相对标准偏差小于3%。CO、CO_(2)的最低检测限分别为0.13μL L和0.26μL L,该方法完全可以满足全密度聚乙烯工艺对异戊烷中微量CO、CO_(2)的质量监控要求。

烷烃脱氢加热炉排烟余热深度回收协同烟压控制性能分析

炼化装置加热炉为石油炼化生产工艺中高能耗、高碳排放设备之一,但低温下烟气冷凝水会腐蚀换热设备,增设排烟余热回收换热设备还会增加烟气系统阻力,对生产工艺造成影响,降低加热炉燃烧效率。排烟余热回收利用系统的防腐、高效、低阻力及烟压控制是余热回收系统能效最大化技术难题。本文以炼化装置加热炉为对象,以烷烃脱氢加热炉为例,提出加热炉低温排烟余热深度回收协同炉膛烟压控制系统方案,采用自主研发的防腐、高效、低阻力排烟余热回收设备,建立加热炉低温排烟余热回收利用节能改造示范工程,并跟踪实测,将实测值与理论值进行对比。结果表明:该系统可将炉膛烟压控制在满足生产工艺要求范围内,控制精度达(-35±6.4)Pa;排烟温度由178.3~178.7℃降至54.3~78.7℃,系统节能率达4.75%~6.9%,烟气余热回收率达28.1%~40.4%,其中梯级换热比单级换热性能提高43.8%,(火用)效率可达52.8%~63.7%,并减少CO_(2)排放2884.5~4197.9t/a,且降低NO_(x)和SO_(2)等污染物排放,节能、减污、降碳效果显著。为炼化装置加热炉的排烟低温余热利用技术开发与应用提供了参考和示范。

高炉液压泥炮打泥压力异常原因分析与判断

该文介绍了高炉液压泥炮工作原理,对打泥压力异常的原因进行了系统性的分析,对泥炮运行过程中的点检维护以及修复验收提供了一种方法,保障了高炉液压泥炮稳定运行。对液压泥炮的打泥压力实行实时监控,并在计算机中绘制压力变化趋势图,根据预先制订的标准对泥炮运行工序时段及打泥压力的数据进行分析,判断液压泥炮打泥系统运行状态,实现了预防性维修。

新钢2500 m^(3)高炉“低压差+低燃耗”管控实践

对新钢2500 m^(3)高炉自大修投产后操作技术进行了分析和总结。高炉以坚持长期稳定顺行为主线,以实现现代高炉“高效、低耗”为目标,不断克服入炉有害元素高、品位低、渣量大、操作炉型不稳定等不利影响。在炉况稳定顺行的基础上,通过持续改善原燃料质量,增强排锌、排碱能力、改善料柱透气性、控制合理渣系、活跃炉缸等技术措施,突破了长期高压差、高燃料比操作技术难题,形成了与自身原燃料条件相适应的“低压差+低燃耗”管控技术。

低氮改造后次高压锅炉炉管失效分析

随着国家对大气污染综合治理的力度越来越大,天津市内的锅炉基本完成低氮改造。目前低氮改造的方式有分级燃烧、预混燃烧和燃气再循环燃烧等。在对某台经过低氮改造的燃气次高压锅炉进行内部检验时,发现其炉管上部普遍存在氧化皮,通过金相检测、硬度检测和壁厚检测等方法对炉管进行检测,并且进行失效分析,提出相应的改进措施。

智能调节炉顶上密封阀夹紧力系统设计

介绍了一种无料钟炉顶上密封阀夹紧力智能控制系统。通过在炉顶称量罐上安装压力变送器,在均压过程中实时检测均压气体压力,计算均压气体对上密封阀板的盲板力,并在液压系统中设置比例减压阀,建立均压气体压力与液压系统压力之间的比例平衡关系,通过计算机系统智能动态调节上密封阀液压系统的压力,降低并均衡上密封阀板与阀座之间的夹紧力,延长上密封阀板、阀座及上密封阀夹紧机构的使用寿命,降低无料钟炉顶上密封阀的故障率,从而保障了高炉炉顶设备运行的高效性。

酒钢中压蒸汽换热器替代管式炉在粗苯工序上的应用

采用中压蒸汽换热器替代管式炉作为粗苯工序的加热设备,从应用效果来看,不论是安全生产水平,还是经济、环保效益,结果表明中压蒸汽换热器加热蒸馏粗苯明显优于管式炉,值得在同行业粗苯蒸馏工序上广泛应用。

浅谈热风炉无波动换炉技术的优势及应用

对热风炉无波动换炉技术优势及应用效果进行了阐述。针对热风炉传统换炉方式存在的弊端,提出了一种热风炉无波动换炉技术,采用独立的供风系统,由空压机供风对热风炉进行充压。热风炉无波动换炉技术除了不会引起风压波动外,还具有可避免风口倒灌、可实现全自动换炉、可提高风温、可提高生铁产量、可降低投资等技术优势。采用无波动换炉技术后,热风炉换炉时间缩短、风温提高,以吕梁建龙1800m^(3)高炉为例,热风炉换炉时间从18min缩短到5min,风温从1170℃提高到1210℃,改造投资额为350万元,回收期仅4个月。

储运中间罐区尾气波动对加氢装置的影响及优化建议

为了解决加氢装置加热炉生产运行期间受储运中间罐区尾气的影响,加热炉炉膛温度及炉出口温度波动较大的问题。本文通过对储运中间罐区尾气压力曲线和尾气控制阀PID参数分析,经过数据对比和参数整定,对储运中间罐区压力控制和尾气控制阀PID参数进行调整,使储运中间罐区尾气控制阀能及时调整到位,从而减少了由此带来的安全隐患和生产波动。