Turbine mixer fundamentals and scale-up method at the Port Nickel Refinery

The Port Nickel Refinery at Braithwaite, Louisiana is being rehabilitated and expanded to achieve a capacity of 80 million pounds per year of nickel. The atmospheric leaching of granulated and ground matte with recirculated and aerated electrolyte from the copper tankhouse is one of the first steps in the Port Nickel flowsheet. An investigation was undertaken to develop the design parameters necessary for the commercial scale-up of this leach circuit. Mechanical factors to be specified include tank geometry, impeller type, and froth handling capability. Also needed for scale-up was quantitative data showing the effect of mixer power and gas input rate on the rate of oxygen transfer. During the leaching period, the rate mechanism changed from oxygen diffusion control to chemical rate control which necessitated careful correlation of the kinetic data with mixer scale-up parameters. The scaled up system calls for a co-current five stage leaching train. Use of a single turbine impeller on a vertical central shaft provides sufficient power for off-bottom solids suspension while providing the required oxygen mass transfer rate. Radial impellers are provided for the first three tanks in which oxygen transfer is rate controlling, and axial impellers for the last two tanks where hydrolysis of basic copper sulfate is the rate controlling factor.     

叶片形状对涡轮桨搅拌槽内尾涡特性的影响

Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their relationship with turbulence properties in a stirred tank of 0.48 m diameter, agitated by four different disc turbines, including Rushton turbine, concaved blade disk turbine, half elliptical blade disk turbine, and parabofic blade diskturbine. Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail. The location, size and strength of vortices were determined by the simplified λ2-criterion and the results showed that the blade shape had great effect on the trailing vortex characteristics. The larger curvature resulted in longer residence time of the vortex at the impeller tip, bigger distance between the upper and lower vortices and longer vortex life, also leads to smaller and stronger vortices. In addition, the turbulent kinetic energy and turbulent energy dissipation in the discharge flow were determined and discussed. High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them. Although restricted to single phase flow, the presented results are essential for reliable design and scale-up of stirred tank with disc turbines.     

桨叶形状对KR法脱硫混合行为影响的数值模拟

为了改善KR搅拌法脱硫剂浪费严重的问题，开发3种新型搅拌桨改善铁水和脱硫剂的混合效果。应用CFD技术，以速度场、湍动耗散率和混匀时间为特征，描述液面的卷入能力和内部混合能力。通过对比3种桨形与传统桨形（A桨）的铁水流动结构，分析结构参数和操作参数之间的影响规律。研究结果表明，方形桨（B桨）卷入脱硫剂的能力和改善混合效果强于其他3种桨形，随转速从60r/min增加到80r/min，柱状回转区体积减小60%，死区体积减小67%，混匀时间缩短52%；D桨的下倾角和径向斜边改善了搅拌桨下方死区混合效果，随转速从60r/min增加到80r/min，死区体积减小51%，混匀时间缩短48%；C桨的卷入能力和混合效果介于D桨和B桨之间；A桨效果最差。     

Cold Model Study on Mg Desulfurization of Hot Metal Under Mechanical Stirring

The new method of in-situ desulfurization with mechanical stirring of new type impellers was introduced,in which the bubble′s dispersion and disintegration of magnesium vapor were the key to boosting the desulfurization efficiency and increasing the utilization rate of magnesium.Effects of different new type of impellers on bubble dispersion and disintegration were studied through bubble image analysis,gas-liquid mass transfer,and power consumption levels of different impeller structures.The results showed that the sloped swept-back blade impeller-2produces optimal bubble′s dispersion and disintegration,as well as higher volumetric mass transfer coefficient and CO2gas utilization while consuming the least power.Numerical simulation result with Fluent software also showed that the sloped swept-back blade impeller-2has higher turbulent kinetic energy and better velocity distribution than the other two impellers.     

半圆管挡板搅拌槽内的固液悬浮

为了提高固液悬浮性能,设计了一种半圆管挡板搅拌槽。采用数值模拟和试验测试相结合的方法,研究了半圆管挡板Rushton桨搅拌槽内石英砂—水的混合特性,分析了固液悬浮特征、固相浓度分布和功率消耗情况,并与标准平直挡板搅拌槽内的悬浮性能进行了对比。结果表明,同一搅拌转速时,半圆管挡板能改善悬浮性能,低固含率(5%)时效果更好。整体而言,半圆管挡板搅拌时石英砂的浓度分布比标准平直挡板搅拌时均匀,而且功率准数低13%左右,节能效应明显。研究结果为半圆管挡板的工业应用奠定了基础。     

Improvement of Impeller Blade Structure for Gas Injection Refining under Mechanical Stirring简

Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central part of the impeller is disk- or plate-shaped, and the blades are fitted to the side of the disk or plate. In addition, a disk is put on the top side of the impeller blades. The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller. These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller. In addition, the sloped swept-back impeller requires less power consumption. The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidi- rectional impeller rotation and without installing baffles. The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath. Highly efficient gas injection refining can be established under the conditions of proper impeller size, larger nozzle immersion depth, larger eccen- tricity and rotation speed of the impeller. The sloped swept back blade impeller can decrease the power consumption and vet improve the bubble disintegration and wide dist~ersion in the bath.     

Characterization of Mixing in Upflow Solids-Contacting Clarifier

It has been recognized that flocculation performance can be related to the mixing process. This process has traditionally been described by vessel average parameters such as the root-mean square velocity gradient ?, which may not represent local mixing conditions within a vessel, particularly in the impeller vicinity. The analysis of turbulence in the flocculator allows a more refined specification of flow, energy, and dissipation, which have long been known to be important to the flocculation process. Presented is a study to characterize hydrodynamic conditions in the impeller zone of an upflow solids-contacting clarifier using a laser Doppler anemometer. Results were analyzed based on an analogy of the impeller-generated flow to a swirling radial jet. It was found that mean and fluctuating velocities scaled on the tip speed of the impeller. Use of the swirling radial jet analogy also allowed the scaling of local dissipation rates. Results compared favorably to other impeller studies and true radial jets, indicating the applicability of concepts for the assessment of other flocculation impellers. It was found that local dissipation rates near the impeller were significantly higher than the vessel average values. These high values highlight the need for further study of the impact of local mixing conditions on flocculation performance.     

圆筒式离心萃取器在锆铪分离中的应用

应用圆筒式离心萃取器对锆铪进行了分离,锆铪皆达到核反应堆可用的纯度。介绍了圆筒式离心萃取器的操作原理,并与混合澄清槽进行了比较,显示了其快速萃取的优点。     

Extraction of cadmium (II) from phosphoric acid media using the di(2-ethylhexyl)dithiophosphoric acid (D2EHDTPA): Feasibility of a continuous extraction-stripping process

The extraction of cadmium from phosphoric media has been studied. The D₂EHDTPA was used as extractant and dodecane as diluent. No third phase was observed in the investigated conditions.A continuous micro-pilot scale mixer-settler was successfully tested for both extraction and stripping. More than 99% extraction rate was obtained in steady-state conditions with a flow rate ratio Aqueous/Organic equal to 1.1. Continuous stripping was performed using HCl 4 M. More than 96% of the cadmium was stripped in one continuous mixer-settler stage for flow rate ratio equal to 0.7. Results were in good agreement with the predicted values based on the McCabe–Thiele method. Experimental mixer-settler stages behave as ideal ones (Murphree efficiency > 98%).An optimal flow sheet is proposed to purify the Wet Phosphoric Acid (WPA) and to recover a relatively concentrated cadmium solution (1 g L^? 1). Two ideal stages operating at phase ratio A/S equal to 5/1 are required for the extraction step leading to a very depleted raffinate (< 0.2 µg L^? 1). For the stripping step, six stages are required (S/A = 5/1). The recovered organic phase contains less than 2 µg L^? 1 and could be recycled in the extraction step.     

Artificial neural network based modeling of liquid membranes for separation of dysprosium

In recent years,the liquid membrane process has been widely investigated to remove rare earth metals.However,transport modeling of this process requires the accurate values of several parameters,which are difficult to measure.Thus,the accurate simulation of this process is a challenging task.In this study,the artificial neural network(ANN) based approach is used to model the liquid membrane process for removing dysprosium.Experimental results from a previous study were used to train the ANN.Init...     

Extraction of palladium (II) from nitric acid medium by imidazolium nitrate immobilized resin

Imidazolium nitrate functional groups (Im–NO₃) were anchored onto a polystyrene–divinylbenzene resin matrix, and investigated for the extraction of palladium (II) from nitric acid medium. The rate of extraction and distribution coefficient, K_d, mL/g, of palladium (II) were measured as a function of extent of functionalization, and concentrations of nitric acid, sodium nitrate and palladium nitrate. K_d values of palladium (II) show a maximum in 3.0 M–4.0 M nitric acid. Slope analysis of the distribution data obtained at various aqueous phase nitrate concentrations and resin phase exchanging capacity suggest the involvement of anion exchange mechanism for the extraction of palladium (II) from nitric acid medium. The ion exchange isotherm was fitted using Langmuir adsorption model and the apparent ion exchange capacity (b = 88 mg/g) was determined. The performance of the resin under dynamic conditions was evaluated by following a breakthrough curve and the data was fitted using Thomas model.     

A solvent extraction study of silver(I), palladium(II) and mercury(II) with 2-tert-dodecylthiopyridine

2-tert-Dodecylthiopyridine was synthesized from 2-chloropyridine and tert-dodecanethiol in order to examine its extraction properties for various metals. It was found to have good selectivity for the extraction of palladium(II) and mercury(II) over platinum(II) and -(IV) and base metals from chloride media; silver(I) was found to be almost completely extracted from nitric acid (0.01–5 mol/dm³ HNO₃). Palladium(II) and mercury(II) were completely extracted from hydrochloric acid over the range 0.01–2 and 0.01–0.5 mol/dm³ HCl, respectively. The rate of extraction of palladium(II) from hydrochloric acid was much faster than when using dialkylsulfide and triisobutylphosphine sulfide extractants. An aqueous mixture of thiourea and hydrochloric acid was found to be effective as stripping solution for palladium(II). The extent of stripping was dependent on the concentrations of either thiourea or hydrochloric acid.     

不对称亚砜BSO萃取分离钯、铂的研究

研究了不对称亚砜(BSO)萃取钯、铂的行为及机理。结果表明:酸度对钯、铂的萃取率和萃取机理有很大影响。在低酸度时,BSO萃取钯主要是中性配位萃取机理,对钯的萃取率接近100%,而对铂的萃取率极低;在高酸度时,BSO萃取钯、铂的机理都是离子缔合萃取,且对钯、铂的萃取率均已接近100%。利用BSO在低酸度下萃取钯、铂可以实现钯、铂的有效分离。氨水为钯的高效反萃剂,蒸馏水为铂的高效、经济反萃剂。     

Separation and recovery of palladium(II) from base metal ions by melamine–formaldehyde–thiourea (MFT) chelating resin

Melamine–formaldehyde–thiourea (MFT) resin, a chelating resin, was synthesized by reaction with melamine, formaldehyde and thiourea in aqueous solution. This chelating resin was used in the separation and recovery of palladium(II) from copper(II) and zinc(II) base metal ions. Effect of initial acidity, adsorption capacities of the metal ions by batch method and adsorption, elution, separation factors and column adsorption capacity of the metal ions by column method were examined. The optimum initial acidity was determined as pH 4. Adsorption capacities of the MFT resin were found as 15.29 mg/g (0.144 mmol/g) for palladium(II), as 1.612 mg/g (0.025 mmol/g) for copper(II) and as 0.453 mg/g (0.007 mmol/g) for zinc(II). In addition the protonation capacity of the resin was found as 0.110 mmol H⁺/g. It was concluded that ionic interaction between protonated amines on the resin and chloro-palladate complex (PdCl₄^2?) was very effective as well as chelation. In the column studies, dynamic adsorption capacities were calculated as 1580 μg/g (14.85 μmol/g) for palladium(II), as 250 μg/g (3.93 μmol/g) for copper(II) and as 25 μg/g (0.38 μmol/g) for zinc(II). MFT resin showed higher affinity to palladium(II) ions according to copper(II) and zinc(II) ions. It was seen that palladium(II) can be separated from copper(II) and zinc(II) and concentrated by melamine–formaldehyde–thiourea chelating resin.     

Alloy Composition Screening for Ni-Base Turbine Disc Superalloys Using the Creep Property of Single Crystal

This paper proposes a method for alloy composition screening using the creep property of a single crystal (SC) for designing new Ni-base powder metallurgy (P/M) turbine disc superalloys. A commercial Ni-base disc alloy, U720Li®, a Ni-Co-base disc alloy, TMW-4M3, and a Ni-base conventionally cast alloy, TM-47, were selected for investigation. Their SC and P/M samples were prepared such that their γ/γ′ structures were similar. Moreover, tensile creep tests were performed on SC samples, and compressive creep tests were performed on SC and P/M samples. The tensile creep test results of SC samples at 1073 K (800 °C) and 735 MPa indicate that 0.2 and 1 pct creep times, as well as rupture life, are long in the order of TM-47 SC, TMW-4M3 SC, and U720Li SC. These results simulate the intragranular creep resistances of the corresponding P/M alloys. Furthermore, there is no significant difference in 0.2 and 1 pct compressive creep times between the SC and P/M samples of each alloy. Additionally, the 0.2 and 1 pct creep times of tensile and compressive creep tests of every alloy had an identical order. Therefore, alloy composition screening using SC creep property enables the design of new disc alloys with excellent creep resistance.

     

Influence of Burden Distribution on Temperature Distribution in COREX Melter Gasifier

 The temperature distribution of COREX melter gasifier was studied by using a two-dimensional 1/30 scale thermal dynamic model. A set of operating conditions, such as radial distribution of direct reduction iron (DRI) to lump coal and coke volume ratio, coke charging location, coke charging amount and coke size, were taken into account. The results show that the temperature near the wall region decreases with the decrease of the radial distribution of DRI to lump coal and coke volume ratio. The temperature with central coke charging is higher than that without central coke column. Furthermore, the temperature significantly increases with the increase of central coke charging amount. With the increase of intermediate coke charging amount, the temperature near the wall region decreases while the temperature in the intermediate region increases. The temperature increases with the increase of coke size whether charging central coke or intermediate coke.     

中钇富铕稀土矿萃取分离新工艺研究

报道了萃取分离中钇富铕稀土矿新工艺，第一步La～Gd/(Gd)TbDy(HoY)/Ho～LuY萃取分离，出口水相La～Gd组份再Nd/Sm分组；中间出口的(Gd)TbDy(HoY)组份Tb/Dy分离。进行了扩大试验和工业生产应用。与中钇富铕稀土Nd/Sm先分组的传统工艺相比，处理能力提高约35%，P507存槽量减少约40%，贵重Tb、Dy稀土从第一步就出口，流程短、收率高。     

Separation of platinum and palladium from chloride solution by solvent extraction using Alamine 300

The separation of platinum and palladium from chloride solution by solvent extraction, using Alamine 300 as an extractant, has been studied. The effect of different parameters such as the concentration of HCl in the feed solution, NaCl concentration, extractant concentration, and platinum and palladium concentrations in the feed solution has been evaluated. Stripping behavior was also studied using different stripping agents, such as sodium thiocyanate and thiourea. Using a saturated solution of sodium chloride at a pH 1.5, platinum was selectively extracted as the major component, along with minor amounts of palladium. By adding a saturated solution of NaCl to the aqueous phase, palladium extraction could be decreased. Additionally, with the use of 0.5 M HCl in place of NaCl, both metals were studied. Selective stripping of platinum accomplished using sodium thiocyanate, and the selective removal palladium was achieved with sodium thiosulfate. This process can achieve a 99.9% purity of platinum even in very dilute solution.     

Neodymium naphthenate-loaded organic phase stripping using sodium oxalate

Neodymium naphthenate-loaded organic phase stripping using sodium oxalate solution was studied to explore the feasibility of synchronous rare earth-loaded organic phase stripping, rare earth precipitation, and blank organic phase saponification. Experimental results show that loaded organic phase stripping, rare earth precipitation, and blank organic phase saponification can be realized simultaneously. When using 20% excess of sodium oxalate over the stoichiometry with the volume ratio of organic phase to aqueous phase of 1:1 at 25 °C for 40 min, the single stage stripping rate and saponification value are about 40% and 0.29 mol/L, respectively. After 16 stages of countercurrent continuous stripping, the stripping rate of neodymium can reach 99%, the saponification value is 0.42 mol/L, the Nd³⁺ concentration in saponified organic phase is less than 0.0020 mol/L, and the main phase in precipitation is Nd₂(C₂O₄)₃·10H₂O. Afterwards, this saponified organic phase can be used in the extraction of NdCl₃ solution, and then the loaded organic phases (neodymium naphthenate) with 0.16 mol/L Nd³⁺ can be retrieved. The morphology, particle size distribution, and composition of the Nd₂(C₂O₄)₃·10H₂O products are similar to those of the current direct precipitation products. The neodymium oxide prepared by continuous calcination of neodymium oxalate meets the national standard of China (GB/T 5240?2015). These results prove the feasibility of stripping neodymium naphthenate-loaded organic phase by using sodium oxalate solution. Sodium oxalate can serve as a stripping agent, a saponifier, and a precipitator, thereby simplifying rare earth extraction and separation. This study provides theoretical and technical support for the development of a novel method for rare earth extraction and separation.     

刚柔组合桨搅拌强化锰矿浸出数值模拟

通过CFD软件对以SO₂气体为还原剂的锰矿浸出过程进行数值模拟,对比刚性单桨、刚性双桨及刚柔组合桨对于气-固-液三相混合强化作用。通过对固相及气相浓度云图分析,比较三种不同结构配置的搅拌反应器对固体颗粒悬浮和气体分散的作用大小,并对搅拌反应器内宏观、介观及其微观混合性能通过轴向和纵向的速度、湍动能及湍动能耗散率进行对比分析。结果表明：刚柔组合桨流场内并未出现颗粒团聚、气体分散不均等现象,并在流场上部对于颗粒悬浮及气体分散作用明显要强于单轴单桨及单轴双桨;刚柔组合桨的宏观、介观及其微观混合性能的表现均优于单轴单桨及单轴双桨。