Hydrometallurgical processing and recovery of molybdenum trioxide from spent catalyst

Hydrometallurgical processing of spent hydrodesulphurisation (HDS) catalyst for the recovery of molybdenum using sodium carbonate and hydrogen peroxide mixtures was investigated. The results indicated that the recovery of molybdenum was largely dependent on the concentrations of Na₂CO₃ and H₂O₂ in the reaction medium, which controls the acidity of the leach liquor and carry over of impurities such as Al, Ni, P, Si and V. Leaching process was exothermic and leaching efficiency of molybdenum decreased with increasing solid to liquid ratio. Large scale leaching of spent catalyst, under optimum conditions: 20% pulp density, 85 g/L Na₂CO₃, 10 vol.% H₂O₂ and 1 h reaction, resulted a leaching efficiency of 84% Mo. The obtained leach liquor contained (g/L): Mo — 22.0, Ni — 0.015 and Al — 0.82, P — 1.1, Si — 0.094 and minor quantities of V — 8 mg/L, As and Co — < 1 mg/L. Recovery of Mo from leach solution as MoO₃ of 97.30% purity was achieved by ammonium molybdate precipitation method.     

Investigations on the extraction of molybdenum and vanadium from ammonia leaching residue of spent catalyst

Extraction of molybdenum and vanadium from ammonia leaching residue (main chemical composition: 2.05% Mo, 0.42% V, 65.6% Al₂O₃ and 10.7% SiO₂) of spent catalyst was investigated by roasting the residue with soda carbonate, followed by hydrometallurgical treatment of the roasted products. In the roasting process, over 91.3% of molybdenum and 90.1% of vanadium could be extracted when a charge containing a sodium carbonate to spent catalyst ratio of 0.15 was roasted at 750 °C for 45 min and the roasted mass was leached with water (liquid to solid ratio of 2) at 80–90 °C for 15 min. After the purification of leach liquor, an extraction solvent consisting of 20 vol.% trialkylamine (N₂₃₅, commercialized in China) and 10 vol.% secondary octyl alcohol (phase modifier) dissolved in sulfonated kerosene was used to extract molybdenum and vanadium in leach liquor. 10 wt.% ammonia water was used as stripping agent. Adding 30 g/l NH₄NO₃ to the stripping solution and adjusting the pH to 7–8.5, over 99% of vanadium can be crystallized as ammonium metavanadate. Over 98% of molybdenum can be crystallized as ammonium polymolybdate when pH is between 1.5 and 2.5 (pH is adjusted by HNO₃). Ammonium metavanadate and ammonium polymolybdate were calcinated at 500–550 °C, the purity of MoO₃ and V₂O₅ was 99.08% and 98.06% respectively. In the whole process, 88.2% of molybdenum and 87.1% of vanadium could be achieved. The proposed roasting, leaching and separation steps give a feasible alternative for the processing of ammonia leaching residue of spent catalyst and can be applied in the comprehensive utilization of low grade molybdenum ores.     

Kinetics of nickel leaching from spent catalyst in sulphuric acid solution

The kinetics of spent nickel oxide catalyst (NiO/Al₂O₃) leaching in sulphuric acid solutions was investigated. The effects of sulphuric acid concentration, temperature, stirring speed, and particle size on the rate of nickel leaching were studied. In addition, the reaction residues at various levels of nickel extraction were examined by SEM, X-ray diffraction, electron microprobe, and chemical analysis. The results of the kinetic analysis of the leaching data for various experimental conditions indicated that the reaction is controlled by diffusion through the catalyst network with the activation energy of 16.6 ± 0.9 kJ/mol. A linear relationship between the rate constant and the inverse square of the initial particle diameter is also characteristic for a diffusion-controlled process.     

微波萃取银杏叶黄酮类化合物

银杏叶黄酮类化合物具有很高的保健和药用价值。采用微波萃取银杏叶黄酮类化合物，与传统溶剂萃取黄酮类化合物方法相比，微波萃取法更简单，而且具有萃取时间短，成本低，萃取效率高等优点。该法适用面更广，能大大提高提取物中黄酮类化合物含量，且溶剂损耗较少。微波辐射5min后抽提1．5h就可以得到较好的效果，而且利用微波处理，在短时间内抽提的提取率按鲜银杏叶重计可达到0．536％，这是传统工艺提取率的2．2倍。     

分光光度法测定钼矿石中钼不确定度评定

对分光光度法测定钼矿石中钼质量分数的不确定度进行评估,建立了数学模型,评定测量过程中不确定度主要来源于曲线拟合,以及重复实验产生的不确定度。当矿石中钼质量分数为0.054%时,评定其扩展不确定度为0.003 0%（k=2）。     

Biosorption of heavy metals by organic carbon from spent mushroom substrates and their raw materials

The use of agricultural wastes as biosorbents is gaining importance in bioremediation of heavy metal-polluted water and soils, due to their effectiveness and low cost. This work assesses the Cd, Pb and Cu adsorption capacity of the raw materials used in the production of substrates for mushroom production (Agaricus bisporus and Pleurotus ostreatus) and the spent mushroom composted (SMC), based on the functional groups of their organic carbon. The raw materials studied included agricultural wastes (wheat straw, wheat and rice poultry litter, grape pomace) and inorganic substances (gypsum and calcareous sand). Organic carbon from wastes and their composting products were characterized by CP-MAS ¹³C NMR. Langmuir adsorption isotherms of metals were plotted for each raw material, composting step, spent A. bisporus and P. ostreatus substrates and the final SMC. The maximum adsorption capacities of SMC were 40.43, 15.16 and 36.2 mg g^?1 for Cd, Pb and Cu, respectively. The composting process modified the adsorption properties of raw materials because of the enhanced adsorption of Cd and Cu and decreased adsorption capacity of Pb. CP-MAS ¹³C NMR and potentiometric titration were used to identify the functional groups of the organic carbon responsible for the metal adsorption. The content of cellulose was correlated with Pb adsorption (p < 0.001), alkyl and carboxyl carbon with Cd adsorption (p < 0.001), and N-alkyl (p < 0.001) and carboxyl (p < 0.010) groups with Cu adsorption. These results are valuable to develop new biosorbents based on agricultural wastes and demonstrate the high potential of SMC to adsorb heavy metals from polluted environments.     

内蒙古陶来托斑岩型钼矿综合找矿信息提取及找矿潜力

对内蒙古陶来托钼多金属勘查区进行地质、地球物理、地球化学综合找矿信息的提取来评价矿区找矿潜力。结果表明,陶来托钼多金属矿是一个以斑岩型钼矿为主的勘查区,发现了斑岩型钼矿床及多处热液脉型铅锌银矿(化)点。成矿岩体为早白垩世花岗斑岩,控矿构造为北东-北北东向断裂。斑岩型钼矿化区与环状激电异常和环状磁异常对应性较好,显示出中低视极化率异常为矿致异常的特征。1∶5万化探异常元素由钼矿化区至铅锌银矿化区表现出Mo、W—Ag、Pb、Zn的侧向分带特征。根据综合找矿信息提取及斑岩型矿床成矿系列建立,指出区内钼矿找矿潜力较大,并预测钼矿区北西侧为热液脉型铅锌银矿的成矿有利地段。     

中国钼矿中辉钼矿的稀土元素地球化学及其应用

钼矿是中国比较特殊的一个矿种,是近年来找矿突破最大的矿种之一。辉钼矿作为最具工业意义的含钼矿物,广泛分布于各种内生钼矿床中。本文尝试性地对内生独立钼矿或共伴生钼矿矿床中的辉钼矿进行了ICP-MS稀土元素分析。结果表明,各矿床辉钼矿中稀土总量在10.99~3374μg/g,集中在10.99~600μg/g。时间上,中侏罗世—早白垩世辉钼矿稀土元素含量最高;空间上,北方矿床中辉钼矿的稀土总量较南方高;矿种组合上,独立钼矿、以钼为主的多金属矿中稀土总量要大于其他伴生钼矿矿床。辉钼矿稀土元素配分曲线具有多样性,不同矿集区内矿床成矿时代、矿床类型与矿种组合对稀土元素配分模式影响不明显。辉钼矿中明显富集轻稀土,具有强烈的Eu负异常(δEu=0.01~0.80)、Ce负异常(δCe=0.24~1.06,多数δCe值<1)和Sm正异常(δSm=1.29~79.42)。依据辉钼矿轻稀土富集程度、Sm和Eu等稀土元素异常特征,将辉钼矿稀土元素配分模式分为6类,反映了不同辉钼矿成因或成矿流体性质的差异性;依据LREE、HREE、δEu和δCe等特征,以及熔体/流体实验结果,推测成钼流体总体上是以富CO2、Cl-(个别还富含F-)和还原性气体成分的成矿流体。内生金属矿床中辉钼矿主要形成于还原性环境,但石英脉型矿床较斑岩型矿床形成条件明显氧化性增强。     

Adsorption of molybdenum on to anatase from dilute aqueous solutions

Adsorption of Mo on to hydrous TiO₂ (anatase) particles was investigated. Batch experiments were conducted at 19 and 90 °C over a pH range of 2 to 12 and Mo concentrations ranging from approximately 10⁻⁶ to 10⁻⁴ M. The extent of sorption was strongly dependent on pH and surface loading. Maximum sorption was observed in the acidic pH range at low surface loading. Adsorption behavior was described using the empirical Langmuir adsorption model. A constant capacitance surface complexation model was also used to fit the adsorption isotherms using a ligand exchange reaction for a hydroxyl surface site on anatase. Comparison of experimental data at two different temperatures (19 and 90 °C) indicates that Mo sorption in the acidic pH range decreases with increasing temperature.     

Leaching study of cesium from spent ion-exchange resins and Portland cement package

The leaching rate of ¹³⁴Cs in cement has been studied. The solidification matrix by a standard Portland cement mixed with the spent ion-exchange resins was previously developed. The leaching rates from cement matrices were measured in function of pH, the immersion and curing times, the resin amounts, and ¹³⁴Cs concentration. In all cases, the leaching rate was deduced from ¹³⁴Cs cumulative activity measured by gamma spectrometry. The study showed that only 11.8% of total ¹³⁴Cs has been leached. This fraction concentrated to the solid surface by silanols has been moved during 34 days through two mechanisms. The Langmuir and Freundlich isotherms attributed these two mechanisms at successive attacks, by water and multilayer and monolayer site formed at the interface package/water. The presence of the spent ion-exchange resins in the matrix, as waste, improves and increases ¹³⁴Cs retention power in the cemented package. In fact, the fraction of ¹³⁴Cs mobilized in the absence of resins (3.18 Bq/Kg) becomes negligible in the presence of 12% of resins.     

从废水中萃取回收铟的工艺研究

采用还原净化,磷酸三丁酯(TBP)共同萃取,稀HCl选择性反萃取分离,二(2-乙基己基)磷酸酯(P204)萃取纯化,HCl反萃取,反萃铟液除杂质,置换和熔炼的湿法冶金新工艺,从废水中回收稀散元素In,可获得合格的粗铟产品,In的质量分数w98.5%,总回收率大于90%。     

中国内生钼矿床辉钼矿的微量元素特征研究

近年来,金属硫化物微量元素研究取得了重大进展,但主要局限于少数常见的硫化物,如黄铁矿。辉钼矿作为内生金属矿床最常见的金属硫化物之一,目前对其微量元素的研究成果还很少,对微量元素的赋存状态及其揭示的成因意义还不明。文章尝试性地对中国57个内生独立钼矿床或共伴生钼矿床中的辉钼矿进行了ICP_MS微量元素分析。结合元素的地球化学性质及前人的研究成果,认为除Re、Os等少数元素可成类质同象存在于辉钼矿中以外,推测大部分微量元素可能以固溶体出溶、机械混入物或流体包裹体等形式存在于辉钼矿中。各矿床中辉钼矿微量元素相对于中国陆壳富集Cu、Zn、Pb、W等常见的成矿元素,暗示不同地质环境下不同时代和矿床类型的成钼流体搬运的成矿元素具有一致性和普遍性,这是造成钼多金属矿床金属元素矿化分带的基础。辉钼矿的主要微量元素呈对数正相关,受矿床类型和产出环境影响不大;辉钼矿Co/Ni比值多数1,集中于0.01~0.57,不同矿床类型的Co/Ni比值具有一定规律性:当w(Co)30μg/g时,斑岩型和矽卡岩型矿床中辉钼矿的Ni含量比较稳定;当w(Co)30μg/g时,Ni含量比较高;石英脉型矿床的Co/Ni比值变化较大,且小于斑岩型矿床的Co/Ni比值。在内生金属矿床中,辉钼矿主要形成于还原性环境中,但石英脉型矿床的形成条件与斑岩型矿床相比,其氧化性明显增强。根据分析结果和前人研究成果,推测成钼流体应为富CO2和Cl-(个别还富含F-)以及部分还原性气体成分(H2、CO、CH4等)的成矿流体。     

Adsorption of oxyanions by spent western oil shale: II. selenite

The adsorption and desorption behavior of selenite by processed Green River Formation oil shales were examined. The selenite adsorption data could be quantitatively described by both the Freundlich and Langmuir isotherms. However, greaterR ² values were obtained for the Freundlich isotherms. Furthermore, selenite adsorption was not a function of the extraction process. The adsorption of selenite by the processed oil shales was irreversible. Upon dilution of the equilibrium systems, additional selenite removal from solution occurred. A thermochemical analysis of the adsorption and desorption equilibrium solutions indicated that the solutions were undersaturated with respect to a number of metal selenite solids. This indicates that precipitation processes are not influencing selenite behavior. However, not all selenite minerals were examined in the evaluation because of the lack of thermochemical data. An insufficient equilibration period for the adsorption study or the alteration of processed oil shale solids as a result of hydration reactions may also have hastened the additional removal of selenite during the desorption studies.     

盐酸羟胺—柠檬酸体系提取土壤中的游离氧化铁

对盐酸羟胺柠檬酸体系（９５℃水浴加热）提取土壤中游离氧化铁的实验条件进行了研究。在所选的实验条件下,该体系对土壤中游离氧化铁的提取能力与常用的连二亚硫酸钠柠檬酸钠重碳酸钠（ＤＣＢ法）体系相当,但避免了ＤＣＢ法中引入Ｎａ２Ｓ２Ｏ４给随后分离和测定造成的沉淀、基体效应等各种弊端。方法的精密度较好,ＲＳＤ（ｎ＝６）为２．５％～３．０％。     

Adsorption of oxyanions by spent western oil shale: I. arsenate

The partitioning of arsenate between Paraho indirectly retorted and directly retorted oil shales and a combusted oil shale was examined with batch equilibrium adsorption isotherms. Arsenate adsorption was found to conform to the Freundlich adsorption model, and the combusted oil shale was found to have the greatest affinity for arsenate. The indirectly and directly retorted oil shale samples did not have statistically different affinities for arsenate. The greater adsorption capacity of combusted oil shale for arsenate was attributed to greater surface area and free iron oxide. Arsenate adsorption by combusted oil shale was not reversible. Upon dilution of the solution phase, arsenate did not desorb. Upon dilution of the retorted oil shale solutions, arsenate continued to be removed from solution. An evaluation of metal arsenate stability in the spent oil shale systems indicated that the retorted oil shale solutions were highly supersaturated with respect to magnesium and barium arsenates, whereas the combusted oil shale solutions were not supersaturated. The data were interpreted to indicate that adsorption reactions control arsenate solubility at short reaction times. As reaction times increase, precipitation reactions control soluble arsenate concentrations.     

Successful Extraction of Low-Grade Ni–Co Ores from Ophiolite-Type Serpentinite by Chinese Experts

正Since the first discovery of the excellent performance of nickel-bearing iron alloys in 1889,scientists have developed3000 more kinds of nickel alloys,which still have an enormous market demand at present.However,the scarcity of global nickel ore resources has restricted economic development.In recent years,experts from the Institute of Multipurpose Utilization of Mineral Resources have studied the comprehensive utilization technique of low-grade nickel ores from     

Biosorption of Cu(II) and Pb(II) from aqueous solutions by chemically modified spent coffee grains

In this research, spent coffee grains were modified with citric acid solutions (0.1 and 0.6 M) to increase the quantity of carboxylic groups improving its metal adsorption capacity. Added functional groups on modified and non-modified spent coffee grains were identified and quantified by attenuated total reflection Fourier transform infrared analyses and potentiometric titrations, respectively. These adsorbents were used for the removal of lead (II) and copper (II) from aqueous solutions at 30 °C and different pH in batch systems. In addition, adsorption–desorption experiments were conducted to evaluate the possibility of re-using the modified adsorbent. Potentiometric titrations data reveal that the quantity of carboxylic groups was increased from 0.47 to 2.2 mmol/g when spent coffee grains were modified with 0.1 and 0.6 M citric acid. Spent coffee grains treated with 0.6 M citric acid, achieved a maximum adsorption capacity of 0.77 and 1.53 mmol/g for lead (II) and copper (II), respectively, whereas non-modified spent coffee grains only reached 0.24 and 0.19 mmol/g for lead (II) and copper (II), respectively. Desorption of lead (II) and copper (II) achieved around 70 % using 0.1 N HCl for non-modified and modified spent coffee grains with 0.6 M citric acid. It is suggested that lead (II) and copper (II) species were adsorbed mainly on the carboxylic groups of modified spent coffee grains and these metals may be exchanged for hydrogen and calcium (II) ions during adsorption on non-modified spent coffee grains. Finally, the adsorption equilibrium was reached after 400 min for modified spent coffee grains with 0.6 M citric acid. Modified spent coffee grains are a promising option for removing metal cations from aqueous solutions due to its low cost and high adsorption capacity (about 10 times higher than the activated carbons).     

Chromium,molybdenum, vanadium,and fluoride sorption from steelwork slag eluates by different mineral additives

Today, the environmental behavior of steelwork slags is very important for their application. When slags are used as building materials, they can interact with water and soil, with the possibility of leaching of harmful components, e.g., metals such as vanadium or anions such as fluoride. The leachable concentrations of various environmentally relevant parameters have to be below defined limit values, which are given by environmental authorities. In this study, different mineral additives have been investigated for their suitability to reduce chromium, molybdenum, vanadium, and fluoride concentrations in slag eluates, as a basis for planned investigations of the long-term leaching behavior of slag/additive mixtures. Seven mineral additives including iron oxide hydroxide, sludge from aluminum production, triple superphosphate, two water work sludges I and II, zeolite powder, and zeolite granules were tested for their efficiency to sorb trace elements and fluoride from four slag eluates comprising two basic oxygen furnace slags and two electric arc furnace slags. The limit values according to the German Alternative Construction Material Ordinance were used to verify which additives were able to minimize concentrations of trace elements and fluoride in slags eluates. Due to high eluate concentrations, the sludge from aluminum production and the triple superphosphate could be excluded from further investigations. The efficiency of the other additives follows the trend iron oxide hydroxide > water work sludges > zeolites. Particularly, the iron oxide hydroxide and the water work sludge I seem to be appropriate to enhance possible applications of slags with respect to the German regulation.