Factors Research on the Influence of Leaching Rate of Nickel and Cobalt from Waste Superalloys with Sulfuric Acid

Unlike the reported leaching technologies of waste superalloys, the process of the “atomized spray-sulfuric acid leaching nickel and cobalt” technology was put forward in the present work according to the compositions of waste superalloys. The effects of sulfuric acid temperature, concentration, leaching time, stirring speed and size of superalloys on leaching of Ni and Co from waste superalloys have been mainly investigated, and the optimum leaching conditions were determined and reported. The leaching rates for nickel and cobalt were 96.68% and 96.63%, respectively, and the contents of nickel and cobalt in leaching slag were 6.77% and 0.96%, respectively. The obtained leaching solution containing Ni and Co could be used for production of Ni and Co products after removal.

Prediction of leaching rate in heap leaching process by grey dynamic model GDM(1,1)

The method of developing GM（1,1） model is extended on the basis of grey system theory. Conditions for the transfer function that improve smoothness of original data sequence and decrease the revert error are given. The grey dynamic model is first combined with the transfer function to predict the leaching rate in heap leaching process. The results show that high prediction accuracy can be expected by using the proposed method. This provides a new approach to realize prediction and control of the future behavior of leaching kinetics.

Numerical analysis of aerated heap bioleaching with variable irrigation and aeration combinations

Forced aeration is an effective way to accelerate the heap bioleaching process.To reveal the effects of different irrigation and aeration combinations on bioleaching performance of copper sulfides,numerical simulations with COMSOL were carried out.Results showed the oxygen concentration is the highest at the bottom with forced aeration,the airflow transports spherically from the aeration pipeline to the slope,and the horizontal diffusion distance is further than vertical value.When the irrigation-to-aeration ratio is higher,the average heap temperatures are mainly decided by aeration rates;otherwise,temperature distributions are the equilibrium of mineral reaction heat,the livixiant driven heat and the airflow driven heat.When the aeration rate is higher than 0.90 m3/(m2·h),oxygen concentration is no longer a limiting factor for mineral dissolution.Additionally,on the premise of sufficient oxygen supply,Cu recovery rate is higher at the bottom with low irrigation rate;while it is higher at upper regions with high irrigation rate.The numerical analysis uncovered some insights into the dynamics and thermodynamics rules in bioleaching of copper sulfides with forced aeration.

Bulk Etch Rate of LR 115 Polymeric Radon Detector

In this study, we used strippable LR 115 type 2 which is a Solid State Nuclear Track Detector (SSNTD) widely known for radon gas detection and measurement. The removed thickness of the active layer of samples of this SSNTD, were determined by measuring the average initial thickness (before etching) and residual thickness after 80 to 135 minutes chemical etching in the standard conditions, using an electronic comparator. These results allowed the calculation of the bulk etch rate of this detector in a simple way. The mean value obtained is (3.21 ± 0.21) μm/h. This value is in close agreement with those reported by different authors. It is an important parameter for alpha track counting on the sensitive surface of this polymeric detector after chemical etching because track density depends extremely on its removed layer. This SSNTD was then used for environmental radon gas monitoring in Côte d’Ivoire.

Assessment of Biofouling Using Leaching Rate of Antifouling Agents and Bioluminescent Assay

The authors investigated the leaching rate of antifouling agents from marine paint using an instrument that allows direct measurement from the flat bottom of ship hulls shortly after dry dock. A similar procedure was also used for painted flat panels that were immersed in the ocean. The relationship between leaching rate and fouling condition was considered by quantifying the amount of ATP （adenosine triphosphate） on the surface of immersed flat panel using fluorescence spectroscopy. The leaching rate results from ship hulls showed good agreement with the value by reporting of leaching rate of antifouling agents. The fluorescence spectroscopy results showed that the amount of ATP on the surface of the panel increased over time as the leaching rate fell, which implies an inverse relationship between leaching rate and fouling index. Fluorescence spectroscopy was also seen to be a simple method for evaluating the relationship between biofouling indexes and leaching rate.

Leaching of heavy metals from Dexing copper mine tailings pond

AThe wastewater source of 4# tailing pond in Dexing copper mine consists of alkaline flotation pulp and acid mine drainage （AMD） from the nearby opencast mine. Therefore, the heavy metals in tailing ore are very likely to be released due to acidification from AMD. The leaching behaviors ofZn, Cu, Fe and Mn in mine tailings from Dexing copper mine were investigated by a series of laboratory batch experiments. The effectcs ofpH, temperature, particle size and contact time on the leachability of such heavy metals were examined. It was evident that Zn, Cu, Fe and Mn were major heavy metals in the tailings while gangue minerals like quartz were major constituents in examined tailings. The tailing dissolution reaction was controlled by the acid, whose kinetics could be expressed according to the heterogeneous reaction models and explained by a shrinking core model with the surface chemical reaction as the rate-controlling step. The leachability of all metals examined depended on pH and contact time. The batch studies indicated that the maximum leaching ratios ofZn, Cu, Fe and Mn at pH 2.0 were 5.4%, 5.8%, l 1.1% and 34.1%, respectively. The dissolubility of all metals examined was positively correlated to the temperatures. The particle size would not change dissolution tendency of those heavy metals, but decrease the concentrations of leached heavy metals.

Recovery of indium by acid leaching waste ITO target based on neural network

The optimized leaching techniques were studied by technical experiment and neural network optimization for improving indium leaching rate. Firstly, effect of single technical parameter on leaching rate was investigated experimentally with other parameters fixed as constants. The results show that increasing residual acidity can improve leaching rate of indium. Increasing the oxidant content can obviously increase leaching rate but the further addition of oxidant could not improve the leaching rate. The enhancement of temperature can improve the leaching rate while the further enhancement of temperature decreases it. Extension leaching time can improve the leaching rate. On this basis, a BPNN model was established to study the effects of multi-parameters on leaching rate. The results show that the relative error is extremely small, thus the BPNN model has a high prediction precision. At last, optimized technical parameters which can yield high leaching rate of 99.5%were obtained by experimental and BPNN studies：residual acidity 50-60 g/L, oxidant addition content 10%, leaching temperature 70 ℃ and leaching time 2 h.

Fe extraction from high-silicon and aluminum cyanide tailings by pretreatment of water leaching before magnetic separation

Pretreatment of high content of Si- and Al-containing cyanide tailings by water leaching to remove some impurities, such as the major impurities minerals of Si and A1, as well as its effect on Fe extraction in the water leaching process was investigated. The effects of different parameters on iron recovery were studied, and the reaction parameters were proposed as follows： sodium carbonate content of 30%, water leaching at 60 ~C for 5 min, liquid/solid ratio of 15：1, and exciting current of 2 A. Under these optimal conditions, magnetic concentrate containing 59.11% total iron and a total iron recovery rate of 76.12% was obtained. In addition, the microstructure and phase transformation of the process of water leaching were studied by X-ray powder diffraction technique （XRD）, Electronic image of backscattering （BEI）, X-ray fluorescence （XRF）, and energy dispersive spectrometry （EDS）. The results indicate that the soluble compound impurities generated in the roasting process are washed out, and the dissoluble substances enter into nonmagnetic materials by water leaching, realizing the effective separation of impurities and Fe.

活性炭纤维固定化菌对微囊藻毒素MC-LR的去除研究

研究了藻蓝蛋白提取过程中微囊藻毒素MC—LR的释放分布规律，并用活性炭纤维对一株微囊藻毒素降解菌株进行了固定化，考察了不同活性炭纤维预处理方法、活性炭纤维用量、pH值、温度以及MC—LR浓度对固定化藻毒素降解菌去除MC—LR的影响．结果表明，藻蓝蛋白提取过程中MC—LR主要分布在超滤滤液中，占MC-LR总含量的81．2％．固定化藻毒素降解菌去除MC—LR的效率明显高于非固定化藻毒素降解菌．藻毒素降解菌用（1十9）盐酸预处理后的活性炭纤维固定化，其去除效果最佳．MC—LR去除的最适条件为：活性炭纤维用量为10g/L，温度为35℃，pH值为8．0．固定化藻毒素降解菌对pH值，温度具有一定的耐受性篇％够在pH5-pH9、10℃-35℃范围内有效地去除MCLR．

高效低时延的LR-WPANMesh地址分配算法

针对IEEE 802.15.5标准中低速率无线个域网(LR-WPAN)Mesh的地址分配算法在地址分配通信开销和时间方面存在冗余的问题,提出一种高效低时延的地址分配(HLAA)算法。该算法通过使用入网申请消息替代专门的地址申请消息和删除地址分配消息中的冗余字段,减少了通信开销并降低了组网时延。仿真结果表明:与现有的低速率无线个域网地址分配算法相比,HLAA算法的通信开销减小了22.15%,组网时延则降低了7.68%。

一种增益可控型LR-WPAN CMOS功率放大器

设计了一种可适应于低速率无线个人区域网(LR-WPAN)的增益可控AB类CMOS射频功率放大器.通过两位数字状态位实现三级增益及输出功率控制,采用片上集成电感和电容实现负载LC回路,有效地提高电路的集成度.采用0.18μm CMOS工艺设计并利用SpectreRF在2.4 GHz ISM频段仿真,实验结果表明,该功率放大器具有较好的性能指标,最小S_(21)参数为13.7 dB,最小输出三阶截断点(P_(OIP3))为6.74 dBm,在输入功率为-10 dBm时最小功率附加效率(PAE)为14.3%,满足LR-WPAN发射模块的要求.

LR-WPAN捷径式能量均衡树路由算法研究

针对LR-WPAN网络中ZigBee树路由算法存在的不足,在综合考虑单个节点的生存周期和整个网络能量消耗的基础上,提出一种捷径式能量均衡树路由算法。通过在节点中使用邻居表以及表中添加动态剩余能量标志位,结合路由跳数、节点和网络的能量状态设计路由算法。运用仿真实验与原始树路由算法进行分析对比,表明改进后的路由算法有效地降低了路由开销和网络节点间的延时,提高了节点存活率和路由效率,达到优化网络能效,延长网络生存周期的目的。

LR-WPAN Mesh网络双重能效优化设计

针对IEEE 802.15.5低速无线个域网(LR-WPAN)标准缺乏能效均衡设计的问题,提出LR-WPAN Mesh网络双重能效优化方法。在自适应树建立和拓扑引导分布式链路状态路由环节中引入合理的能效评估要素,优化拓扑结构和路由选择。实验结果表明,双重能效优化方法可使网络寿命延长97%,并使网络的能耗更加均衡。

Nitrogen Runoff and Leaching Losses During Rice-Wheat Rotations in Taihu Lake Region,China

Although nitrogen （N） loss through runoff and leaching from croplands is suspected to contribute to the deterioration of surrounding water systems, there is no conclusive evidence for paddy soils to prove this hypothesis. In this study, field plot experiments were conducted to investigate N losses through runoff and leaching for two consecutive years with 3 N fertilization rates in rice （Oryza sativa L.）-wheat （Triticum aestivum L.） rotations in the Taihu Lake region, China. A water collection system was designed to collect runoff and leachates for both the rice and wheat seasons. Results showed that dissolved N （DN）, rather than particulate N （PN）, was the main form of N loss by runoff. The NO3^--N concentration in runoff was between 0.1 and 43.7 mg L^-1, whereas the NH4^＋-N concentration ranged from below detection limit to 8.5 mg L^-1. Total N （TN） loads by runoff were 1.0-17.9 and 5.2-38.6 kg ha^-1 during rice and wheat seasons, respectively, and the main loss occurred at the early growing stage of the crops. Nitrogen concentrations in leachates during the rice seasons were below 1.0 mg L^-1 and independent of the N application rate, whereas those during the wheat season increased to 8.2 mg L^-1 and were affected by the fertilizer rate. Annual losses of TN through runoff and leaching were 13.7-48.1 kg ha^-1 from the rice-wheat cropping system, accounting for 5.6%-8.3% of the total applied N. It was concluded that reduction in the N fertilization rate, especially when the crop was small in biomass, could lower the N pollution potential for water systems.

Characteristics of leaching of heavy metals from low-sulfur coal gangue under different conditions

Coal gangue is the main pollution source of mining areas.When coal gangue is stacked and recycled,the heavy metal elements contained in it are released by natural weathering and leaching,which causes damage to the surrounding ecological environment.In this study,the leaching and precipitation characteristics of heavy metals in low-sulfur coal gangue under different environmental conditions were simulated by indoor dynamic leaching experiments,which provided a theoretical basis for environmental restoration of the mining area.The conclusions are as follows:higher heavy metal content in low-sulfur coal gangue is associated with greater,leaching of heavy metals;acidic conditions promote the release of heavy metals in low-sulfur coal gangue;and more precipitation is associated with better release of heavy metals from the low-sulfur coal gangue.

Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution

A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaC12 aqueous solution, liquid-to-solid （L/S） ratio, leaching temperature, and leaching time, were inves- tigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy （SEM） and X-ray diffraction （XRD）. On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min-1, a CaC12 aqueous solution concentration of 400 g·L-1, a liquid-to-solid mass ratio of 7：1, a leaching tempera- ture of 80℃, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.

Sulfuric acid leaching of high iron-bearing zinc calcine

Sulfuric acid leaching of high iron-bearing zinc calcine was investigated to assess the effects of sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, and the stirring speed on the leaching rates of zinc and iron. The results showed that the sulfuric acid concentration, liquid-to-solid ratio, leaching time, and leaching temperature strongly influenced the leaching of zinc and iron, whereas stirring speed had little influence. Zinc was mainly leached and the leaching rate of iron was low when the sulfuric acid concentration was less than 100 g/L. At sulfuric acid concentrations higher than 100 g/L, the leaching rate of iron increased quickly with increasing sulfuric acid concentration. This behavior is attributed to iron-bearing minerals such as zinc ferrite in zinc calcine dissolving at high temperatures and high sulfuric acid concentrations but not at low temperatures and low sulfuric acid concentrations.

Insight into the structural evolution of porous and fractured media by forced aeration during heap leaching

Despite lots of techniques in improving the heap leaching performance,many constraints on the industrial applications remain.We proposed a correspondingly effective and new idea of introducing forced aeration to improve the bad permeability and leaching effect of Yangla Copper Mine(YCM)during heap leaching.The dual-media theory was employed to study the impact mechanism of forced aeration on the variations of porous and fractured media during the column leaching experiments.An X-Ray Computed Tomography(CT)set was utilized to perform the pore imaging of the specimens and the fracture morphology of the particles within the columns was analyzed by Scanning Electron Microscope(SEM)as aeration rate(AR)changed.The results show that there exists copious fine particles within the heap of YCM,the particle size distribution of which is not reasonable.The forced aeration can not only promote the development of the porous and fractured structures but effectively break the blocked seepage paths.Then the leaching degree is improved and the seepage performance of the solute within the solution is enhanced.Therefore,the forced aeration is probable of making the leaching performance greatly improved.

Effects of microwave pretreatment on zinc extraction from spent catalyst saturated with zinc acetate

A new technology for microwave pretreatment of spent catalyst on Zn extraction by HCl leaching was proposed and the temperature-change curve of spent catalyst under microwave irradiation was measured.The influence of microwave pretreatment temperature and microwave irradiation time on zinc extraction was investigated and the mechanism of microwave pretreatment for spent catalyst was analyzed.The results show that microwave pretreatment can greatly enhance the leaching rate of Zn.The Zn extraction reaches 96.58%under the conditions of microwave pretreatment temperature of 950℃and the microwave irradiation time of 12 min.The blocked pores of spent catalyst can be opened through microwave pretreatment,increasing the contact area of leaching reagent and zinc.

Experimental Study of Preferential Solute Transportation During Dump Leaching

The production of dump leaching of the Dexing Copper Mine was affected by a preferential solution flow. Formative mechanism of the preferential solution flow was investigated by analyzing the relationship between both dump permeability and surface tension and ore diameter. The preferential solution flow occured in the fine ore area when the application rate was low. The preferential solution flow entered into the coarse ore area because the negative pore water pressure disappeared with an increase of the application rate. The preferential solute transportation experiment was conducted by selecting NaCl as mineral. Results of the experiment showed that the concentration of the outflow solution reduced over time. The concentration of the coarse ore area outflow solution was greater than that of the fine ore area. The process of NaCl leaching can be divided into two stages. NaCl was carried out directly by diffusion--convection during the first stage, so the leaching rate increased sharply. But in the second stage, only a small amount of NaCl dissolved in the immobile water. The leaching rate increased slowly because NaC1, dissolved in the immobile water, can only be leached by diffusion.