Ammonium Metavanadate Fabricated by Selective Precipitation of Impurity Chemicals on Inorganic Flocculants

High purity ammonium metavanadate(NH_(4)VO_(3))is the most vital chemical to produce V2O5,VO2,VN alloy,VFe alloy and VOSO4,which have some prospective applications for high strength steel,smart window,infrared detector and imaging,large scale energy storage system.NH_(4)VO_(3)is usually produced by spontaneous crystallization from the aqueous solution due to its sharp dependence of solubility on the temperature.However,hazardous chemicals in industrial effluent,include phosphorate,silicate and arsenate,causing severe damage to the environment.In this work,these impurities are selectively precipitated onto inorganic flocculants,while the vanadate dissolved in an aqueous solution keeps almost undisturbed.Therefore,high purity NH_(4)VO_(3)is produced by the crystallization from the purified solution.By screening various flocculants and precipitating parameters,polyaluminum sulfate with an optimal amount of 50 g/L,is demonstrated to selectively remove phosphorate,silicate and arsenate,corresponding to the removing efficiency of 93.39%,97.11%and 88.31%,respectively.NH_(4)VO_(3)from the purified solution holds a purity of 99.21%,in comparison with 98.33%in the product from the crude solution.This purifying technology cannot only produce NH_(4)VO_(3)with high added value,but also reduce the environmental pollution of waste liquid.

Cyclic metallurgical process for extracting Ⅴ and Cr from vanadium slag: Part Ⅰ. Separation and recovery of Ⅴ from chromium-containing vanadate solution

The separation and recovery of V from chromium-containing vanadate solution were investigated by a cyclic metallurgical process including selective precipitation of vanadium,vanadium leaching and preparation of vanadium pentoxide.By adding Ca(OH)_(2) and ball milling,not only the V in the solution can be selectively precipitated,but also the leaching kinetics of the precipitate is significantly improved.The precipitation efficiency of V is 99.59%by adding Ca(OH)_(2) according to Ca/V molar ratio of 1.75:1 into chromium-containing vanadate solution and ball milling for 60 min at room temperature,while the content of Cr in the precipitate is 0.04%.The leaching rate of V reaches 99.35%by adding NaHCO_(3) into water according to NaHCO_(3)/V molar ratio of 2.74:1 to leach V from the precipitate with L/S ratio of 4:1 mL/g and stirring for 60 min at room temperature.The crystals of NH_(4)VO_(3) are obtained by adjusting the leaching solution pH to be 8.0 with CO2 and then adding NH_(4)HCO_(3) according to NH_(4)HCO_(3)/NaVO_(3) molar ratio of 1:1 and stirring for 8 h at room temperature.After filtration,the crystallized solution containing ammonia is reused to leach the precipitate of calcium vanadates,and the leaching efficiency of V is>99%after stirring for 1 h at room temperature.Finally,the product of V_(2)O_(5) with purity of 99.6%is obtained by calcining the crystals at 560℃ for 2 h.

Cyclic metallurgical process for extracting V and Cr from vanadium slag: Part Ⅱ. Separation and recovery of Cr from vanadium precipitated solution

Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO_(3)and leaching with Na_(2)CO_(3)was investigated.The concentration of Cr residue in the solution decreases from 2.360 to 0.001 g/L by adding PbCO_(3)into vanadium precipitated solution according to Pb/Cr molar ratio of 2.5,adjusting the pH to 3.0 and stirring for 180 min at 30℃.Then,the precipitates were leached with hot Na_(2)CO_(3)solution to obtain leaching solution containing Na_(2)CrO_(4)and leaching residue containing PbCO_(3).The leaching efficiency of Cr reaches 96.43%by adding the precipitates into 0.5 mol/L Na_(2)CO_(3)solution with the mass ratio of liquid to solid(L/S)of 10:1 mL/g and stirring for 60 min under pH 9.5 at 70℃.After filtration,leaching residue is reused in Cr precipitation and leaching solution is used to circularly leach the Cr precipitates until Na_(2)CrO_(4)approaches the saturation.Finally,the product of Na_(2)CrO_(4)·4H_(2)O is obtained by evaporation and crystallization of leaching solution.

Thermodynamic analysis on reaction behaviors of silicates in (NH_4)_2WO_4-(NH_4)_2CO_3-NH_3-H_2O system

The reaction behaviors of silicate species in （NH4）2WO4-（NH4）2CO3-NH3-H2O system are crucial to developing a greenmanufacture technique for ammonium paratungstate. In order to efficiently remove silicon from the system, the reaction behaviors ofsilicate species were systematically investigated by thermodynamic analysis. The thermodynamic analysis shows that silicate in thetungstate clinker partly decomposes in the leaching process, with 150-160 mg/L silicon thermodynamically at 25 ℃. The dissolvedsilicon can be removed by magnesium salts via forming insoluble MgSiO3. The low carbonate and high ammonia concentrations inthe system are beneficial to the removal of silicon, with silicon concentration reaching 8-10 mg/L thermodynamically, whereasMgSiO3 precipitation is hardly formed when the concentration of total carbonate is more than 1.5 mol/L. The reaction behaviors ofcalcium and magnesium were also studied in the system. The results in the verification experiments consist with the theoreticalcalculation.

钒钛磁铁矿提钒尾渣钙化碱浸试验研究

由于钒钛磁铁矿提钒尾渣中Na2 O含量高,作为炼铁配矿使用时会造成高炉结瘤问题,难以规模化利用。本文针对此问题,以承钢钒钛磁铁矿提钒尾渣为原料,进行了钙化碱浸-偏钒酸铵沉钒试验,目的是对提钒尾脱碱的同时提取其中有价金属钒。试验主要考察了浸出温度、碱浓度、氧化钙添加量和液固比对钠和钒浸出率的影响,结果表明,在浸出温度160℃、碱浓度100 g·L^(-1)、氧化钙添加量15%、液固比6:1、浸出时间60 min的条件下,钒和钠的浸出率分别达到82.25%和85.36%;对含钒碱浸液进行偏钒酸铵沉钒,得到了纯度大于97%的V_(2)O_(5)产品;终渣中Na_(2)O含量小于0.5%,Fe_(2)O_(3)含量达到30.10%,结合承钢高炉的碱金属平衡数据,可满足高炉炼铁配矿使用。本文研究结果可为相关企业钒钛磁铁矿提钒尾渣的规模化利用提供参考。

弱酸性铵盐沉钒工艺条件研究

本文研究了淅川钒矿钠化焙烧物料水浸液弱酸性铵盐沉钒的工艺条件，结果表明，多钒酸铵沉钒的最佳工艺条件为：沉钒ｐＨ值为６．０，ＮＨ＿４Ｃｌ加入量３０ｇ／Ｌ，搅拌时间９小时。在该工艺条件下，若浸出液中Ｖ＿２Ｏ＿５含量大于６．５ｇ／Ｌ，多钒酸铵沉钒率≥９７％。

钒酸钙碳化铵化生产钒氧化物的反应规律

以钒渣亚熔盐法钒铬共提工艺所得到的中间产品钒酸钙为研究对象,针对钒酸钙后续产品转化问题,提出钒酸钙碳化铵化生产钒氧化物的工艺路线;研究NH_4HCO_3转化溶出钒的工艺条件,考察是否通入CO_2、NH_4HCO_3的添加量、反应温度、不同液固比以及反应时间等对钒酸钙转化溶出效果的影响。结果表明:钒酸钙碳化铵化反应的最佳条件为反应温度75℃,液固比20:1,通入CO_2,且流速1.5 L/min,铵钒摩尔比1.0,反应时间1h,此条件下钒酸钙中钒转化率为97.35%。

酸性铵盐沉钒制备高纯V_2O_5的试验研究

以石煤提钒水浸—离子交换所得富钒液为研究对象,分析了富钒液中钒及杂质含量,以及酸性铵盐沉钒pH值、温度、时间、铵盐类型和加铵系数等因素对制备高纯V2O5的影响。试验结果表明,采用酸性铵盐沉钒,在最佳工艺条件下可制备高纯度粉体V2O5。

我国钒页岩提钒技术研究现状及前景

综述了近十年来我国在钒页岩提钒领域的重要研究成果,包括选矿预富集、焙烧、浸出、净化富集及沉钒等方面的研究现状和最新进展。重点探讨了典型难处理云母型钒页岩焙烧、浸出、净化富集和沉钒技术的研究工作及最新研究成果,同时介绍了一些新兴强化钒高效提取的方法在钒页岩提钒领域的应用及机理。空白焙烧工艺适用于钒赋存形式简单且多赋存于氧化物中的钒页岩,而对于钒赋存形式复杂的钒页岩,钒的转价率较低;添加剂焙烧工艺能够有效破坏含钒矿物晶体结构,强化低价态钒的释放和氧化。直接酸浸工艺能有效浸取以吸附形式存在的钒页岩中钒,而对于钒以类质同象形式赋存于云母类矿物中的页岩适用性较差;助浸剂及新兴外场浸出工艺能进一步强化含钒矿物晶格破坏,显著提高钒的浸出率;新型净化富集技术能实现钒与杂质离子的高效分离富集,提高分离过程的适用性和环保性;新型无铵沉钒工艺可从源头消除传统铵盐沉钒工艺过程的氨氮及大气污染等环境问题,并获得高附加值钒产品。后续应基于钒页岩工艺矿物学研究,进一步开发高效、低能耗的提钒技术;同时,探讨提钒技术基础理论,阐明提钒工艺过程控制因素,优化提钒工艺参数,降低生产成本,为我国钒页岩提钒行业绿色可持续发展提供理论及技术支撑。

利用(NH_4)_2SO_4分步盐析法从麦芽中初步分离极限糊精酶

文中对极限糊精酶的(NH4)2SO4盐析法进了研究。从大麦芽中萃取得到的粗酶液,采用(NH4)2SO4盐析法进行粗分级提取,绘制盐析曲线,确定盐析法纯化极限糊精酶的方案,并研究了各方案对极限糊精酶纯化纯度和得率的影响。研究结果表明:盐析曲线中饱和度分别为35%和80%时出现两个酶活峰,但80%饱和度时可以将绝大部分酶蛋白沉淀;分别采用一步法盐析(80%),二步法盐析(25%,80%),三步法盐析(25%,35%,80%)沉淀酶蛋白,其中三步法盐析可使极限糊精酶的纯度(A510/A280)达到1.635,纯化倍数和得率分别为8.8倍和49.5%,均优于其他两种方法。极限糊精酶盐析方案的优化可为其进一步分离纯化奠定基础。

石煤沸腾焙烧料提取五氧化二钒工艺研究

针对石煤沸腾焙烧料提钒原料差异大、工艺流程过长、钒回收率低(大多低于60%)、成本偏高等问题,采用拌酸熟化浸出-氧化中和-离子交换-铵盐沉钒-煅烧的工艺路线提钒。实验结果表明,在硫酸用量为原料质量的20%、熟化温度100℃、熟化时间6 h的条件下,石煤沸腾焙烧料中的钒浸出率达到90.2%,最终制备得到的产品V_(2)O_(5)粉末质量稳定可靠,达到了行业标准水平。该工艺流程短,工程建设投资低、钒回收率高、提钒冶炼成本低,取得了较好的经济技术指标。

分步结晶技术在酸性铵盐沉钒废水处理中的应用

五氧化二钒生产过程中会产生大量的酸性铵盐沉钒废水。在经还原、中和处理后的沉钒废水依然含有大量的钠盐、铵盐。本文介绍了沉钒废水处理现有的主要处理方式,阐述了分步结晶技术处理酸性铵盐沉钒废水的工艺流程,总结出了该技术的难点。

钙盐沉钒的热力学研究

根据同时平衡原理以及质量守恒定律，绘制了在不同的游离总钙浓度下Ca-V（V）-H2O体系25℃时的热力学平衡图，并进行了热力学分析。结果表明，随着溶液pH值的增大，体系中依次出现V2O5、Ca（VO3）2、CazV2O7、Ca3（VO4）2、Ca3（VO4）7＋Ca（OH）2、Ca（OH）2六个沉淀稳定区。当沉钒反应平衡后液游离总钙浓度为0．01mol／L时，在pH=5．1～9．8范围内，钒以Ca（VO3）。形式沉淀，钒浓度最低可降至2．2×10^-3mol／L；在pH-9．8～10．3范围内，钒以Ca2V2O7形式沉淀，钒浓度最低可降至1．2×10^-2mol／L；在pH=10．3～12．6范围内，钒以Ca3（VO4）2形式沉淀，钒浓度最低可降至2．4×10^-4mol／L，沉钒效果最佳。当游离总钙浓度为0．01～1．0mol／L时，理论最佳沉钒pH值基本维持在11．0～12．6。

高浓度钒液沉钒工艺研究

研究了采用酸性铵盐沉钒方法，从含钒３０ｇ／Ｌ左右的高浓度钒液中沉淀多钒酸铵的工艺条件及对五氧化二钒质量的影响。实验室试验和扩大试验结果表明，钒沉淀率大于９９％，五氧化二钒产品质量达到国家标准。

从碱性含钒溶液中萃取钒的研究

采用碳酸根型季铵盐为萃取剂从碱性含钒溶液中萃取钒,考察了萃取剂浓度、改性剂浓度、萃取温度、时间、相比、pH对钒萃取率的影响.结果表明,碳酸根型N263从碱性溶液中萃取钒的机理是阴离子交换机理,适宜的萃取条件为：温度20～40℃、接触时间1 min、相比O/A=1/2;只考虑萃取率和分相时间时,有机相中合适的N263浓度为0.091 9 mol/L.

利用失效钒电解液回收钒制备偏钒酸铵工艺

为了提取失效钒电解液中有价钒元素,对全钒氧化还原液流电池失效钒电解液的回收利用进行了研究。在常温常压条件下,以氯酸钠作氧化剂对失效钒电解液进行深度氧化,使低价钒全部转变成五价钒,然后通过浓缩、沉钒、干燥等工艺过程,得到具有高附加值的偏钒酸铵。分析了回收过程的工艺原理,探讨了回收工艺的工艺条件。结果表明:NaClO_3对失效钒电解液的氧化是影响钒回收率的关键工艺过程,V^(4+)∶NaClO_3的最佳摩尔比为1∶0.2,V^(3+)∶NaClO_3的最佳摩尔比为1∶0.4;沉钒的最佳工艺条件为:钒液浓度为25~30g/L,p H为8.0~8.5,沉钒温度为50~60℃,加铵系数K为1.0~1.2,沉钒时间为80~120min。该工艺具有钒回收率高、成本低、操作简便、对环境友好等优点,在最佳工艺条件下钒的回收率可高达99%左右,为全钒液流电池失效钒电解液的回收利用提供了一条新途径。

用硝酸铵复盐沉淀法制备高纯硝酸铈铵

研究了以硝酸铵复盐沉淀法制备高纯硝酸铈铵,考察了不同条件对硝酸铈铵氧化率、收率、重金属杂质质量分数的影响,对比了高、低温2种条件下制备的产品质量。结果表明:硝酸铵复盐沉淀法所制备的硝酸铈铵的组成为(NH4)2[Ce(NO3)6];最佳条件下制备的产品中,∑REO质量分数大于31%,重金属杂质质量分数小于1.0×10-5,产品氧化率大于98.5%,纯度很高。

从废弃的钨金属制品中回收钨和钒

研究和开发了一种从废弃的钨金属制品中回收钨和钒的新工艺。该工艺包含三个步骤 :①联合使用镁盐和铝盐对钨金属制品碱浸出液的纯化 ;②利用甲酸选择性地浸出钒 ;③高纯APT的结晶。通过该工艺的处理 ,钨金属制品浸出液中的钒浓度可从 0 .175 g/L提高到 1.380g/L。结果 ,86 96%金属钒以偏钒酸铵的形式被回收 ,85 %以上的金属钨以APT(仲钨酸铵 )的形式被回收 ,APT的纯度达到了日本的国家产品 (一级品 )

滤液法和沉淀法测定宁夏枸杞果实醇提物中季铵型生物碱的含量

以宁夏枸杞为试材,基于季铵型生物碱与雷氏盐的反应原理,采用分光光度法测定宁夏枸杞果实醇提物中季铵型生物碱含量,建立了宁夏枸杞果实醇提物中季铵型生物碱的含量测定方法。结果表明:滤液法与沉淀法的平均回收率分别为97.57%与98.06%,RSD分别为1.02%与1.10%(n=6)。由此看出,滤液法与沉淀法用于季铵型生物碱的含量测定,所得结果基本一致,滤液法操作相对简便。

沉钒条件对沉钒率的影响研究

随着科技的发展,五氧化二钒的应用领域不断扩大,对钒产品纯度的要求也越来越高。本文采用弱碱性铵盐沉钒法进行实验,通过实验得出最优沉钒条件为:加铵系数K=1.5,p H值7.5,反应温度50℃,反应时间为40 min,沉钒率达到95%以上,V2O5含量在97%以上。为高纯五氧化二钒的工业化生产提供方向性参考。