铝循环过程的物质流分析——框架、数据与待解的问题

铝在社会经济系统中的物质流动过程可概括为"3个4":4个阶段,4种库,4种流。其中,铝的循环过程是指从废杂铝到再生铝的物质流动过程,包括回收、处理和熔铸三个主要环节。相应地,存在回收所得率、处理所得率、熔铸所得率和综合循环利用率4级循环指标。在此框架下,本文对比分析了我国废杂铝、再生铝和循环指标的数据,提出为完善铝物质流分析还需要解决的关键问题及相应对策。

铝循环二次铝灰生产氧化铝实验研究

铝循环过程中产生大量二次铝灰,未经妥善处理既污染环境又造成铝资源浪费。本文以铝再生熔炼过程产生的二次铝灰为原料,经水浸预处理、盐酸浸出、碱沉淀、纯化、再沉淀、焙烧等工艺制备高纯氧化铝。探讨了沉淀、纯化、焙烧的最佳条件,结果表明:加氨水调节pH至8.5,再加NaOH调至13,固液分离后,75℃下向滤液中加入聚乙二醇2000,完全溶解后,滴加HCl调节pH至9.5,陈化10h,得到的前驱体为三羟铝石,纯度高,结晶好,在700℃下煅烧前驱体得到纯度为99.2%的γ-Al_(2)O_(3),1200℃下煅烧得到的产物为α-Al_(2)O_(3)。

中国2003年至2007年铝循环分析

本文给出了铝的物质循环流图,铝循环的整个过程包含4个阶段:氧化铝和电解铝的生产阶段,铝制品的加工制造阶段,铝制品的使用阶段和报废铝制品的回收阶段。采用此物质循环流图分析了我国2007年的铝循环状况,得出了以下指标:氧化铝生产阶段、原铝生产阶段和整个铝工业的原料自给率分别为55.50%、79.25%和49.01%;整个铝工业自产废杂铝和进口废杂铝的使用比例分别为5.93%和9.35%。给出了我国2003年—2007年铝工业的物流指标,得出了此阶段原料自给率和废杂铝使用比例的变化。分析了我国2003年—2007年间各种含铝物质的净进口量、铝循环中各种含铝物质损失量和铝社会蓄积量净增量的变化。并给出了我国今后铝工业进出口政策的重点和减少铝损失的工作重点。

百色市铝产业循环经济发展投融资问题研究

铝工业属于资源型、资金密集型产业,是百色市的支柱产业。发展铝产业循环经济是实现百色市经济可持续发展的根本途径。而在市场经济条件下,投融资不仅是非常重要的市场化调控和引导手段,更是百色市发展铝产业循环经济成败的关键。本文通过分析百色市铝产业循环经济发展投融资存在的问题,进而提出改善投融资的对策建议,以促进产业循环经济发展。

低碳背景下广西循环生态型铝工业发展的选择

铝工业是公认的高能耗、高污染、资源消耗型的产业。能源问题是制约广西铝工业发展的瓶颈。在节能减排背景下,广西铝工业面临生存与发展的压力。文章分析了广西铝工业发展的状况及其碳源特征,提出向"水能→水电→铝液→铝深加工"产业集群一体化方向发展低碳的循环生态型的广西铝产业。

百色市发展铝产业循环经济的投融资现状及对策

在百色市的实际发展过程中,铝产业是其非常重要的产业之一,对百色市经济水平的提升,具有十分重要的作用和意义。近年来,国家重视程度的不断提升,百色市更是成为了国务院批复的生态铝产业示范基地。当前,由于社会发展速度提升的越来越快,国家对于循环经济的重视程度也在逐渐提升。所以,百色市也积极迎合社会发展,认真贯彻这一理念。然而,由于一些因素的制约,使得百色市发展铝产业循环经济的投融资还存在了一些问题以及弊端,对此,需要制定合理对策,有效对这一现状进行缓解。

铝卷材退火炉热风循环系统暨循环加热炉的改进设计

本实用新型循环系统适用于铝卷材退火炉。针对以往铝材退火炉炉温均匀性不能达到客户要求等问题现特提出研发铝卷材循环加热退火炉。本新型采用高温变频可逆调速轴流风机技术,使炉内气氛均匀流动;炉口密封采用新型密封材料;提高了炉膛利用率;保证铝箔时效处理温度均匀性误差小于等于±3℃。

用物质流分析方法研究中国铝工业矿石指数和铝土矿资源效率

研究物质流来源于人们对工业生态学的认识,也就是人们希望建立类似于自然生态系统的循环工业体系,物质流分析(Materials Flow Analysis,MFA)方法是发展循环经济的一个重要的技术支撑。本文通过利用物质流分析的典型方法 -欧拉法,从铝的生命周期的角度研究铝循环的重要指标,揭示铝行业发展现状,探寻可持续发展方向。

废铝合金复化处理设备及工艺研发

介绍了废铝合金复化处理,研发了双室炉设备及技术,使纯金属氧化烧损比传统技术降低75%～80%,大气污染物排放优于国标,从而实现了绿色环保生产。

硅藻生物硅中铝的赋存及其生物地球化学效应

硅藻是铝生物地球化学循环的重要驱动者。淡水和海洋硅藻均可对铝进行捕获,并将其作为构建硅藻生物硅的骨架元素。由此,铝在硅藻生物硅“携带”下迁移和循环,并通过降低硅藻生物硅的溶解度对其固碳效应等产生重要影响。本文主要从硅藻和铝的生物-元素界面作用机制、铝在硅藻生物硅中的赋存特征以及铝对硅藻生物硅的“生物泵”效率的影响及机制三方面,介绍铝的生物地球化学循环受硅藻驱动的机制以及铝在硅藻生物硅中赋存所引起的地球化学效应,最后提出相关研究面临的挑战和亟待解决的一些问题。

草原绿色生态环保“建设者”--内蒙古霍煤鸿骏铝电公司煤电铝超低排放项目侧记

作为内蒙古地区煤电铝循环经济绿色发展中的支柱产业,霍煤鸿骏铝电公司深入践行习近平生态文明思想,积极探索以生态优先、绿色发展为导向的高质量发展路径,加大草原生态系统保护力度,打好铝电解污染防治攻坚战,守护好祖国北疆这道靓丽风景线。

铝与生态环境

通过对矿产金属铝生产的全过程破坏植被、占用土地和三废物质产生及排放进行分析,探讨了铝的生产对生态环境的影响。同时分析了铝用阳极、氟化盐和电力生产对生态环境的影响,验证了矿产金属铝属于高环境代价产品。通过对铝的应用和回收价值进行分析,验证了铝的循环利用价值和环境意义。

Analysis of anthropogenic aluminum cycle in China

Anthropogenic aluminum cycle in China was analyzed by the aluminum flow diagram based on the life cycle of aluminum products. The whole anthropogenic aluminum cycle consists of four stages： alumina and aluminum production, fabrication and manufacture, use and reclamation. Based on the investigation on the 2003-2007 aluminum cycles in China, a number of changes can be found. For instance, resources self-support ratio （RSR） in alumina production dropped from 95.42%to 55.50%, while RSR in the aluminum production increased from 52.45%to 79.25%. However, RSR in the Chinese aluminum industry leveled off at 50%in the period of 2003-2007. The respective use ratios of domestic and imported aluminum scrap in the aluminum industry of 2007 were 5.38% and 9.40%. In contrast, both the net imported Al-containing resources and the lost quantity of Al-containing materials in aluminum cycle increased during the same period, as well as the net increased quantity of Al-containing materials in social stock and recycled Al-scrap. Proposals for promoting aluminum cycle were put forward. The import/export policy and reducing the loss of Al-containing materials for the aluminum industry in China in the future were discussed.

Recovery of alumina from circulating fluidized bed combustion Al-rich fly ash using mild hydrochemical process

To utilize CFBC Al-rich fly ash, a mild hydrochemical extraction process was investigated for recovery of alumina. An alumina extraction efficiency of 92.31%was attained using a 45%NaOH solution, an original caustic ratio （molar ratio of Na2O to Al2O3 in the sodium aluminate solution） of 25, a molar ratio of CaO to SiO2 in the fly ash of 1.1, a liquid volume to solid mass ratio of 9, a reaction temperature of 280 ℃, and a residence time of 1 h when treating fly ash with an alumina to silica mass ratio （A/S） of 0.78 and an alumina content of 32.43%. Additionally, the alumina leaching mechanism was explored via structural and chemical analysis, which revealed that after alkaline digestion, the main solid phase containing silica was NaCaHSiO4 with a theoretical A/S of zero.

Numerical simulation of ductile fracture behavior for aluminum alloy sheet under cyclic plastic deformation

A numerical analysis of mechanical behavior of aluminum alloy sheet under cyclic plastic deformation was investigated.Forming limit at fracture was derived from Cockcroft-Latham ductile damage criterion.The strain path of bending center of incremental roller hemming could be accepted as a kind of plane strain bending deformation process.Incremental rope roller hemming could be used to alleviate ductile fracture behavior by changing the stress state of the hemming-effected area.SEM observation on the fracture surface indicates that cyclic plastic deformation affects ductile fracture mechanism.

Electrochemical behavior of Li incorporation in Al in LiTFSI/KTf molten salt electrolyte

The electrochemical behavior of lithium incorporated in aluminum electrode in LiTFSI/KTf （lithium bis （trifluoromethylsulfonyl） amide/CF3SO3K） molten salt electrolyte was studied by a variety of electrochemical techniques including cyclic voltammetry, chronopotentiometry and chronoamperometry. The reduction reaction is found involving a nucleation process on the aluminum electrode. The results of chronopotentiometry indicate that the process of lithium incorporation in aluminum is smooth and uniform. The galvanostatic cycle experiments show that the coulombic efficiency is very low in the first cycle, which is mainly due to the ＂retention capacity＂ of Li-Al alloys. This characteristic is testified by the results of XRD and SEM. The results of chronoamperometry indicate that the incorporation of lithium into aluminum for the formation of a-phase Li-Al alloy is limited by its diffusion rate, with a measured diffusion coefficient of 1.8× 10^-10 cm2/s.

Effects of electrolyte recycling on desulfurization from bauxite water slurry electrolysis

To lower the cost of bauxite electrolysis desulfurization using NaOH solution as the supporting electrolyte, effects of electrolyte recycling on bauxite electrolysis desulfurization were investigated. The results indicate that electrode corrosion, cell voltage, the desulfurization rate and the pH value of the electrolyte have no obvious changes with the increase of cycle times. Additionally, there were some transitive valence S-containing ions in electrolyte after the electrolysis, such as SO3^2-,S2O3^2- . However, most of the sulfur in bauxite was eventually oxidized into SO4^2- into the electrolyte, and these S-containing ions did not affect the recycling utilization for electrolyte.

Enhancing corrosion resistance of 7150 Al alloy using novel three-step aging process

The effects of a novel three-step aging process （T76＋T6） on the electrochemical corrosion behavior of 7150 extruded aluminum alloy were evaluated and compared with those of the conventional retrogression and re-aging process （T77）. The open circuit potential （OCP）, cyclic polarization and electrochemical impedance spectra （EIS） of the A1 alloys were measured after treatment in three solutions （3.5% NaCl （mass fraction）; 10 mmol/L NaCl ＋ 0.1 mol/L Na2SO4; 4 mol/L NaCl ＋ 0.5 mol/L KNO3 ＋ 0.1 mol/L HNO3）. The parameters including the corrosion potential, pitting potential, pit transition potential and steepness, and potential differences were extensively discussed to evaluate the corrosion behavior of the Al alloys. The electrochemical and scanning electron microscopy （SEM） data show that compared with the 7150-T77 Al alloy, the T76 ＋ T6 aged 7150 A1 alloy exhibits better resistance to pitting corrosion, inter-granular corrosion （IGC） and exfoliation corrosion, which is attributed to further coarsening and inter-spacing of the grain boundary particles （GBPs） as revealed by transmission electron microscopy. Furthermore, the hardness tests indicate that an attractive combination of strength and corrosion resistance was obtained for the 7150 Al alloy with T76 ＋ T6 treatment.

Void damage evolution of LF6 aluminum alloy welded joints under external load and thermal cycling conditions

Based on the simulated aerospace thermal cycling tests,the effect of thermal cycle on the void damage evolution mechanism of LF6 aluminum alloy welded joint was investigated.The results show that micro-voids form around the second phase particles under the thermal cycling tests.The thermal stress coupled with external stress leads to dislocations pile-up around the particles,and when the dislocation density reaches a certain degree,the stress concentration will exceed the bonding strength at the interface between particles and matrix,resulting in the formation of micro-cracks.The numerical simulation is successfully implemented with the finite element to describe the void damage evolution of the welded joint under thermal cycling conditions.

Electrochemical behavior of tantalum in ethylene carbonate and aluminum chloride solvate ionic liquid

To investigate the electrochemical reduction mechanism of Ta(Ⅴ)in ethylene carbonate and aluminum chloride(EC-AlCl3)solvate ionic liquid,cyclic voltammetry experiments were conducted on a tungsten working electrode.Four reduction peaks were observed in the cyclic voltammogram of the EC-AlCl3-TaCl5 ionic liquid.The reduction peaks at-0.55,-0.72,and-1.12 V(vs Al)were related to the reduction of Ta(Ⅴ)to tantalum metal by three stages including the formation of Ta(Ⅳ)and Ta(Ⅲ)complex ions.The reduction of Ta(Ⅲ)to tantalum metal was an irreversible diffusion-controlled reaction with a diffusion coefficient of 3.7×10^-7 cm^2/s at 323 K,and the diffusion activation energy was 77 k J/mol.Moreover,the cathode products at 323 K were characterized by scanning electron microscopy,energy-dispersive spectroscopy,and X-ray photoelectron spectroscopy.The results showed that tantalum metal and tantalum oxides were obtained by potentiostatic electrodeposition at-0.8 V for 2 h.