钒钛渣碱浸脱硅

研究一种选择性脱除钒钛渣中二氧化硅的工艺。利用XRD、SEM和EDS对钒钛渣和碱浸出后的样品进行表征。结果表明：钒钛渣的主要组分是黑钛石、辉石和金属铁。黑钛石为板状和颗粒状,分布于辉石中;金属铁为球型,呈蠕虫状被包裹于辉石和黑钛石中,边缘被氧化;硅主要分布在辉石中;钛和钒主要分布在黑钛石中。对搅拌速度、浸出温度、浸出时间、NaOH浓度和液固比对浸出的影响进行研究。结果表明：浸出温度和液固比对Si02的浸出率有较大的影响,在最佳实验条件下,Si、A1、Mn和v的浸出率分别为88．2％、66．3％、27．3％和1．2％。钒钛渣碱浸脱硅动力学过程受化学反应控制,其表观活化能为46．3kJ／mol。     

纳米六方水合铝酸钙的制备与应用

采用液相沉淀法制备了纳米六方水合铝酸钙(C4AHx),在单因素实验的基础上,通过正交实验确定了合成纳米六方水合铝酸钙的最佳工艺条件。采用XRD、SEM对脱硅剂进行物相和粒度形貌分析,探讨其脱硅机理。在最佳条件下添加纳米六方水合铝酸钙进行深度脱硅,脱硅后的铝酸钠溶液中SiO2含量可降低到0.007 g/L,硅量指数可达14000。     

伊利石在铝酸钠溶液中的反应脱硅过程研究

为了更清楚地了解伊利石在拜耳法溶出过程中的反应行为，本文对伊利石在合成铝酸钠溶液中的溶出动力学进行了研究，测得其活化能为114，73kJ/mol。并研究了溶液苛性碱浓度对伊利石的反应速率的影响；添加石灰可以有效的增加伊利石的反应率，提高脱硅效率。为拜耳法生产氧化铝的脱硅过程及防止结疤提供理论依据。     

铝酸钠溶液添加硫酸钙脱硅过程的研究

以硫酸钙作为脱硅剂,对铝酸钠溶液脱硅条件和结果进行了研究。实验中考察了脱硅温度、脱硅时间、脱硅剂的用量、搅拌速度对脱硅效果的影响,确定了最佳脱硅工艺条件:在95℃的温度下添加硫酸钙30g/L深度脱硅90min,精制液的硅量指数达3681。对硫酸钙脱硅后所形成的硅渣进行XRD测定,并且对硫酸钙的脱硅机理进行了分析。     

Vapor pressure and thermochemical properties of ZrCl4 for ZrC coating of coated fuel particles

Vapor pressure of zirconium tetrachloride（ZrCl4）under vacuum and an argon pressure of 1 × 105 Pa was measured. The thermochemical changes of ZrCl4 during evaporation were studied by thermogravimetry-differential thermal analysis（TG-DTA）, X-my diffractometry（XRD）, scanning electron microscopy（SEM） and energy-dispersive X-ray（EDX） analysis. At the same temperature, vapor pressures of ZrCl4 under vacuum and an argon pressure of 1× 10^5 Pa are approximately the same. The vapor pressure exceeds 1 × 10^5 Pa at 340 ℃, which is high enough for ZrC coating of coated fuel particles. ZrCl4 sample is hydrolyzed to some extent to give ZrO2 and HCl, which however, has little influence on vapor pressure of ZrCl4 at high temperature. No ZrCl3 and Cl2 are produced by decomposition of ZrCl4 during evaporation, which is confirmed by thermodynamic calculation.     

Preparation of Ti-rich material from titanium slag by activation roasting followed by acid leaching

A method of activation roasting followed by acid leaching using titanium slag was introduced to prepare Ti-rich material. The effects of H₃PO₄ dosage, roasting temperature, and roasting time on TiO₂ grade were investigated. A Ti-rich material containing 88.54% TiO₂, 0.42% (CaO+MgO) was obtained when finely ground titanium slag was roasted with 7.5% H₃PO₄ at 1000 °C for 2 h, followed by a two-stage leaching in boiling dilute sulfuric acid for 2 h. The XRD patterns show that the product is titanium dioxide with a rutile structure. Mechanism studies show that structures of anosovite solid solution and silicate minerals are destroyed in the roasting process. As a result, titanium components in titanium slag are transformed into TiO₂ (rutile) while impurities are transformed into acid-soluble phosphate and quartz.     

机械活化强化钒渣钙化提钒工艺

针对转炉钒渣钙化焙烧酸浸工艺中存在的钒转浸率低的问题,采用高能球磨对钒渣进行活化预处理,以期强化其提钒效果。采用激光粒度分析仪、BET比表面积测定仪和XRD对活化前后钒渣进行了粒度、比表面积及物相结构分析;采用浸出实验研究了机械活化对钙化焙烧和浸出的影响规律。结果表明:机械活化法增大了钒渣的比表面积,增加了晶格畸变与微观应力,使含钒物相充分解离,由此可改善钒渣钙化焙烧的动力学条件。在浸出20 min条件下,机械活化80 min可将钒浸出率提高10%,最佳焙烧温度降低100℃。     

Surface Cleaning or Activation？Control of Surface Condition Prior to Thermo-Chemical Heat Treatment

Actual heat treatment processes must face increasing specifications with reference to process quality, safety and results in terms of reproducibility and repeatability. They can be met only if the parts‘ surface condition is controlled during manufacturing and, especially, prior to the treatment. An electrochemical method for the detection of a steel part‘s surface condition is presented, together with results, consequences, and mechanisms concerning surface pre-treatment before the thermochemical process. A steel surface‘s activity or passivity can be detected electrochemically, independently from the chemical background. The selected method was the recording of potential vs. time curves at small constant currents, using a miniaturized electrochemical cell, a (nearly) non-destructive electrolyte and a potentio-galvanostatic setup. The method enables to distinguish types of surface contamination which do not interfere with the thermochemical process, from passive layers which do and must be removed. Whereas some types of passive layers can be removed using conventional cleaning processes and agents, others are so stable that their effects can only be overcome by applying an additional activation pre-treatment, e.g. oxynitriding.     

Effect of mechanical activation on the production of SiC from silica sand

In this study the effect of 100 and 200 h low energy ball milling on the carbothermic reduction of SiO₂ and C powder mixture was investigated. Microstructure studies of the mixture by SEM revealed that the particle size had been decreased and the SiO₂ particles had been covered by C particles due to the milling. The results of thermal analysis (TG-DTA) of milled and unmilled mixtures clearly showed that the reduction temperature decreased due to milling process. XRD pattern of 200 h activated mixture proved that β-SiC had been formed almost completely after reduction at 1500 °C.     

Influence of crystal structure on mechanical activation effect

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｗｅｌｌａｃｋｎｏｗｌｅｄｇｅｄｔｈａｔｉｎｔｅｎｓｅｍｅｃｈａｎｉｃａｌａｃ ｔｉｏｎｍａｙｃａｕｓｅｒｅｍａｒｋａｂｌｅｉｎｃｒｅａｓｅｉｎｒｅａｃｔｉｖｉｔｙｏｆｓｏｌｉｄｓ .Ａｌｏｔｏｆｂａｓｉｃｒｅｓｅａｒｃｈｉｎｆｉｅｌｄｓｏｆｇｅｏｌｏｇｙ[1] ,ｍｅｔａｌｌｕｒ ｇｙ[2 6] ,ａｓｗｅｌｌａｓｃｈｅｍｉｃａｌｅｎｇｉｎｅｅｒｉｎｇ[3 ] ,ｈａｓｓｈｏｗｎｔｈａｔｐｒｅｓｓｕｒｅａｎｄｓｔｒｅｓｓａｒｅｃｏｎｃｅｎｔｒａｔｅｄａｔｔｈｅｃｏｎｔａｃｔｓｉｔ…     

Technology and mechanism of desilication from roasted diasporic bauxite in atmosphere

The leaching desilication technology of roasted diasporic bauxite in atmosphere by caustic soda solution was investigated. The optimum parameters were: the grinding fineness of the roasted bauxite -0. 076 mm and 80 % -85 %,leaching time 2h, Na2Ok100-150g/L, L/S 4-5, leaching temperature 90-95℃. The desilication rate 55.20% and concentrate A/S (mass ratio of A12O3 to SiO2) 9.90, as good as those obtained at pressure, were obtained respectivdy.Investigation of two-stage leaching shows that it can both improve desilication rate of roasted ore and reduce leaching time.When time of the first stage and the second stage is 30 min and 30 min respectively, desilication rate can reach 59.65 %.X-ray diffraction analysis of the concentrate has proved that desilication procedure is accompanied with the formation of sodium aluminosilicate hydrate. X-ray spectra also show that silica removed during leaching is amorphous silica. SiO2 occurrina as ouartz in raw ore or mullite formed during roasting can not dissolve in alkali solution.     

Atmospheric corrosion evaluation of galvanised steel by thin layer activation

The release of certain metals, such as zinc, from outdoor constructions due to atmospheric corrosion is of some concern. For risk assessments the evaluation of the amount of released metal is of importance. Various methods can be used to study the release of metals. These include those using radiotracers, such as thin layer activation (TLA). To verify the reliability of TLA with respect to conventional techniques in the evaluation of atmospheric corrosion, galvanised steel was exposed to a mild marine environment. The amount of zinc in the corrosion products, released through artificial leaching, at different time intervals was evaluated by TLA and atomic absorption spectroscopy (AAS). A good correlation between the results was found indicating the feasibility of TLA for these release studies.     

机械活化对从复杂硫化精矿中硫代硫酸盐浸取金的影响

采用机械活化提高复杂硫化矿CuPbZn中金的回收。研究研磨时间、球尺寸、球料比和球磨转速对金的硫代硫酸盐浸取的影响。在最优条件下（球磨时间1h,球尺寸20mm,球料比15/1,球磨速度600r/min）,矿石的非晶化度达到78%,颗粒尺寸从30μm下降到8um,比表面积从1.3m2/g增加到4.6m2/g,金的回收率从7.4%提高到73.26%。     

木瓜蛋白酶对MPA形成及其诱导的单核细胞活化的影响

目的: 观察木瓜蛋白酶对单核细胞-血小板聚集物(MPA)形成及其诱导的单核细胞活化的抑制作用,并初步探讨其作用机制。方法: 分离单核细胞和富血小板血浆(PRP),将实验分为3组:0、20、80 U/L 木瓜蛋白酶组,分别测定不同浓度木瓜蛋白酶与单核细胞和血小板(PLT)共孵育后以及木瓜蛋白酶与血小板单独孵育后MPA形成、P-选择素和CD11b表达水平,木瓜蛋白酶与单核细胞孵育后的MPA形成和CD11b表达水平,计算各浓度木瓜蛋白酶对MPA和CD11b的抑制率。结果: 随药物浓度增加,木瓜蛋白酶与单核和PLT共孵育后以及木瓜蛋白酶与血小板单独孵育后MPA形成、P-选择素和CD11b表达水平显著降低,木瓜蛋白酶与单核细胞单独孵育后MPA形成和CD11b表达水平显著降低,差异均有统计学意义(P<0.01 或 0.001)。各处理组中,80 U/L 组对MPA和CD11b的抑制率均显著高于 20 U/L 组(P<0.01),木瓜蛋白酶与血小板和单核细胞共孵育组MPA和CD11b抑制率均显著高于其余两组,差异均有统计学意义(P<0.001)。结论: 木瓜蛋白酶可通过抑制血小板P-选择素表达和单核细胞与血小板结合途径而对MPA形成及其诱导的单核细胞活化有抑制作用,这可能作为其可应用于抗血栓和动脉粥样硬化防治的新机制。     

芦苇浆造纸黑液资源化处理新工艺

针对芦苇浆造纸产生的浓缩黑液的特点,提出了黑液脱硅—酸析回收木质素—三维电极电解—苛化回收NaOH—出水返回生产的工艺流程。采用Ca(OH)2沉淀法去除黑液中的SiO2,黑液中硅含量由6.68 g/L降至0.12g/L,脱硅率为98.20%;黑液脱硅后加入H2SO4去除COD并回收木质素,CODCr由220.648 g/L降至54.179 g/L左右,脱除率达到75.45%,每100 mL黑液可回收8.5 g木质素。FTIR、SEM和EDX的分析结果表明:酸析木质素结构以紫丁香基和对羟基的单体结构为主;采用三维电极反应器处理酸析液,残余CODCr为36.761 g/L,TOC的去除率达35.57%;利用苛化法回收残碱,用于制浆蒸煮工段,实现废水的零排放。苛化后的黑液中有效碱浓度为8.30 g/L,苛化度为78.60%,苛化后TOC降低了9.99%,残余CODCr浓度为33.085 g/L,可返回生产,实现了资源的综合回收与利用。     

The activation of aluminium by mercury ions in non-aggressive media

The presence of Hg at concentration less than 300 ppm in Al base alloys causes their passivation breakdown. On alloys used as sacrificial anodes, it causes a major lowering (>0.3 V) in their operational potential in chloride media. Mercury as trace constituent in the natural gas stream causes severe damage to cryogenic heat exchangers. The present paper presents evidences of the mechanism by which mercury produces its pronounced effect in aqueous non-aggressive media. The work was carried out using pure (99.99%) aluminium and mercury (II) acetate solutions of different concentrations and pH. Open circuit potential–time responses were obtained. The surface effects were followed by means of scanning microscopy and EDAX/X-Ray analysis. The results demonstrate that immediately after immersion, the initial air-formed oxide film underwent a dynamic crack–healing process at flaws in the film, possible associated to grain boundaries. The subsequent healing process, if any, depends on the media composition. Thus, in this special case, Hg²⁺ ions can be directly reduced on the bare aluminium, reaching a true metallic contact, and initiating surface diffusion. This enables the formation of an amalgam. Aluminium atoms diffuse through the liquid mercury and undergo oxidation at the amalgam/electrolyte interface. This process is responsible for the oxide detachment (by undermining) and the attack morphology (i.e., wide cavities).The presence of aggressive anions is not needed to initiate activation.     

Diffusion activation enthalpy of nanocrystalline metals

lINTR0DUCTIONNanocrystalline(NC)materialsarePOly-crystalswithacrystallitesizeontheorderofnanometers.Duetothesmallcrystallitesize,NCmaterialsconsistofahighdensityofthein-terfaces.Itissuggestedthatthestructureofthecrystallinec0mPOnentdeviateslittlefromthat0fthebulk,whereastheinterfaceshowsan'ex-tendedstructure'duetotheexistenceofalargeamountoffreevolume,whichprovidesahighdensenetworkofpathsf0rfastdiffusioninNC..t..i.l.[1~3].Thereby,thediffusionactivationenthalpyofNCmaterialsisexpectedto…     

低品位菱镁矿选矿脱硅技术研究

根据伊朗某地菱镁矿的成矿特性和矿石工艺矿物学特性,提出了低品位菱镁矿选矿脱硅“一次磨细-正浮选”的工艺。通过“一次磨细-正浮选”流程的系统试验,获得了较好的技术指标。     

Effect of mechanical activation on TiC synthesis reaction in Al-Ti-C powder mixture

1　ＩＮＴＯＲＤＵＣＴＩＯＮＭｅｃｈａｎｉｃａｌａｃｔｉｖａｔｉｏｎｉｓａｋｉｎｄｏｆｐｒｅ ｔｒｅａｔｍｅｎｔｔｅｃｈｎｏｌｏｇｙｉｎｐｒｏｄｕｃｔｉｏｎｏｆｃｏｍｐｏｓｉｔｅｓ ,ｅｓｐｅｃｉａｌｌｙｐａｒｔｉｃｌｅｒｅｉｎｆｏｒｃｅｄｍｅｔａｌｍａｔｒｉｘｃｏｍｐｏｓｉｔｅｓ .Ｉｔｉｎ ｃｌｕｄｅｓｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｅｌｆ ｐｒｏｐａｇａｔｉｎｇｓｙｎｔｈｅｓｉｓ[1] ,ｈｏｔ ｐｒｅｓｓｉｎｇｓｙｎｔｈｅｓｉｓ[2 ,3 ] ａｎｄｉｎ ｓｉｔｕｌａｓｅｒｓｙｎｔｈｅ ｓｉｓ[4 ,5] ｅｔｃ .Ｄ…     

Surface chemistry of activation of lime-depressed pyrite in flotation

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｕｎｄａｍｅｎｔａｌｂｅｈａｖｉｏｒｏｆｐｙｒｉｔｅｆｌｏｔａｔｉｏｎｈａｓｂｅｅｎｗｉｄｅｌｙｉｎｖｅｓｔｉｇａｔｅｄ .Ｔｈｅｓｅｌｆ ｉｎｄｕｃｅｄｆｌｏｔａｔｉｏｎｏｆｐｙｒｉｔｅｏｃｃｕｒｓｏｎｌｙｉｎｓｔｒｏｎｇｌｙａｃｉｄｉｃｓｏｌｕｔｉｏｎ[1] .Ｔｈｅｐｏｏｒｓｅｌｆ ｉｎｄｕｃｅｄｆｌｏｔａｔｉｏｎｏｆｐｙｒｉｔｅｉｓｕｓｕａｌｌｙｄｕｅｔｏｉｔｓｓｕｒｆａｃｅｏｘｉｄａｔｉｏｎｔｏｏｘｙ ｓｕｌｐｈｕｒｓｐｅｃｉｅｓ[1～ 5] .Ｈｏｗｅｖｅｒ ,ｐｙｒ…