Study on synergistic leaching of potassium and phosphorus from potassium feldspar and solid waste phosphogypsum via coupling reactions

To achieve the resource utilization of solid waste phosphogypsum(PG)and tackle the problem of utilizing potassium feldspar(PF),a coupled synergistic process between PG and PF is proposed in this paper.The study investigates the features of P and F in PG,and explores the decomposition of PF using hydrofluoric acid(HF)in the sulfuric acid system for K leaching and leaching of P and F in PG.The impact factors such as sulfuric acid concentration,reaction temperature,reaction time,material ratio(PG/PF),liquid–solid ratio,PF particle size,and PF calcination temperature on the leaching of P and K is systematically investigated in this paper.The results show that under optimal conditions,the leaching rate of K and P reach more than 93%and 96%,respectively.Kinetics study using shrinking core model(SCM)indicates two significant stages with internal diffusion predominantly controlling the leaching of K.The apparent activation energies of these two stages are 11.92 kJ·mol^(-1)and 11.55 kJ·mol^(-1),respectively.

Selective leaching of lithium from spent lithium-ion batteries using sulfuric acid and oxalic acid

Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable metals.In this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids.Under optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and oxalates.This study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.

Recovery of Li, Ni, Co and Mn from spent lithium-ion batteries assisted by organic acids: Process optimization and leaching mechanism

The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous substances.In this study,a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium(Li),nickel(Ni),cobalt(Co),and manganese(Mn)from spent LIBs using sulfuric acid with citric acid as a reductant.The effects of the concentration of sulfuric acid,the leaching temperature,the leaching time,the solid-liquid ratio,and the reducing agent dosage on the leaching behavior of the above elements were investigated.Key parameters were optimized using response surface methodology(RSM)to maximize the recovery of metals from spent LIBs.The maxim-um recovery efficiencies of Li,Ni,Co,and Mn can reach 99.08%,98.76%,98.33%,and 97.63%.under the optimized conditions(the sulfuric acid concentration was 1.16 mol/L,the citric acid dosage was 15wt%,the solid-liquid ratio was 40 g/L,and the temperature was 83℃ for 120 min),respectively.It was found that in the collaborative leaching process of sulfuric acid and citric acid,the citric acid initially provided strong reducing CO_(2)^(-),and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state.Additionally,citric acid can also act as a proton donor and chelate with lower-priced transition metal ions,thus speeding up the dissolution process.

Extraction of Valuable Metals from Titanium-bearing Blast Furnace Slag by Acid Leaching

To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparation of calcium carbonate” was proposed.In this study,the influences of process conditions on the leaching rates of calcium,magnesium,aluminum,and iron and the phases of the leaching residue were investigated for the leaching process.The experimental results show that the HCl solution could selectively leach the elements from the titanium-containing blast furnace slag.The better leaching conditions are the HCl solution concentration of 4 mol/L,the leaching time of 30 min,the ratio of liquid volume to solid gas of 10 mL/g,and the stirring paddle speed of 300 r/min.Under the conditions,the leaching rates of calcium,magnesium,aluminum,and iron can reach 85.87%,73.41%,81.35%,and 59.08%,and the leaching rate of titanium is 10.71%.The iron and the aluminum are removed from the leachate to obtain iron-aluminum water purification agents,and the magnesium is removed from the leachate to obtain magnesium hydroxide.The leaching residue phase is dominated by perovskite,followed by magnesium silicate and tricalcium aluminate,and the titaniumrich material could be obtained from the leaching residue by desiliconization.

Preparation of sodium molybdate from molybdenum concentrate by microwave roasting and alkali leaching

The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient development of molybdenum concentrate resources,this paper proposes a new process for efficient recovery of molybdenum from molybdenum concentrate and preparation of sodium molybdate by microwave-enhanced roasting and alkali leaching.Thermodynamic analysis indicated the feasibility of oxidation roasting of molybdenum concentrate.The effects of roasting temperature,holding time,and power-to-mass ratio on the oxidation product and leaching product sodium molybdate (Na_(2)MoO_(4)·2H_(2)O) were investigated.Under the optimal process conditions:roasting temperature of 700℃,holding time of 110 min,and power-to-mass ratio of 110 W/g,the molybdenum state of existence was converted from MoS_(2) to Mo O3.The process of preparing sodium molybdate by alkali leaching of molybdenum calcine was investigated,the optimal leaching conditions include a solution concentration of 2.5 mol/L,a liquid-to-solid ratio of 2 mL/g,a leaching temperature of 60℃,and leaching solution termination at pH 8.The optimum conditions result in a leaching rate of sodium molybdate of 96.24%.Meanwhile,the content of sodium molybdate reaches 94.08wt%after leaching and removing impurities.Iron and aluminum impurities can be effectively separated by adjusting the pH of the leaching solution with sodium carbonate solution.This research avoids the shortcomings of the traditional process and utilizes the advantages of microwave metallurgy to prepare high-quality sodium molybdate,which provides a new idea for the highvalue utilization of molybdenum concentrate.

Effect of Saline Water on Soil Acidity, Alkalinity and Nutrients Leaching in Sandy Loamy Soil in Rwamagana Bella Flower Farm, Rwanda

The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K+), Magnesium (Mg2+), Sulphur (S), CN ratio and Sodium (Na+) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.

基于遗传算法和蚁群算法的LEACH改进协议

针对无线传感器网络低功耗自适应集簇分层(Low Energy Adaptive Clustering Hierarchy,LEACH)路由协议因能耗不均衡导致节点过早死亡的问题,提出了一种基于遗传算法和蚁群算法改进的LEACH路由协议。在分簇阶段,通过遗传算法选举合理的簇头节点并根据节点的分布划分簇群;在数据传输阶段,通过蚁群算法使簇头节点尽可能选择能量充足且距离较短的路径进行数据传输。仿真结果表明,与传统的分簇路由协议LEACH和LEACH-C相比,改进算法可以使网络的能量消耗更加均衡,并延长网络的生命周期。

无线传感器网络LEACH协议的改进

为提高经典LEACH路由协议的功能表现,解决因选取过程中簇头节点过于集中带来的相关问题,对LEACH协议中簇首的选取以及簇首到基站的通信进行优化。从原理上详细分析LEACH的算法原理,并在此基础上提出改进的LEACH路由算法。改进算法在簇首选取过程中考虑节点的剩余能量和空间位置,在数据稳定传输阶段采用多跳方式传递数据。通过MATLAB进行仿真实验,结果显示改进后的LEACH算法有助于减少节点的能量消耗,延长了网络节点的生命周期。

无线传感器网络LEACH算法的改进与仿真分析

对无线传感器网络分簇路由协议中LEACH算法进行了研究,针对算法中簇头节点随机选取、节点能量分布不均等不足之处,提出一种基于节点剩余能量、邻居密度与基站相对距离等因素改进的LEACH算法。改进后的算法通过网络最低能耗计算得出最优簇头数目,在簇头选取阶段,优化簇头的阈值计算公式,使节点剩余能量高、节点邻居数目多、相对基站距离近的节点更容易成为簇头。利用MATLAB软件,对LEACH算法、HEED算法及改进的LEACH算法的性能进行了仿真分析和比较。实验结果表明,改进的LEACH算法的网络整体能耗要低于LEACH算法和HEED算法,并显著地延长了网络的生存时间。

基于最优簇头数的LEACH改进算法研究

在LEACH协议的基础上,计算出最优簇头数,并使用数学期望值法计算得到簇头节点与普通节点之间最佳距离。仿真结果表明,改进后的LEACH协议降低了网络能耗,增长了网络存活时间,增加了数据发送总量。

基于簇头节点能量均衡选择的LEACH优化算法

针对无线传感网络中LEACH协议在进行簇头节点选择时能量消耗过快导致的生存周期短、数据吞吐量低等问题,提出了一种基于簇头节点能量均衡选择的LEACH优化算法。该算法选取WSNs中剩余能量高的普通节点作为簇头节点,同时考虑普通节点与簇头节点、簇头节点与基站之间的距离,以及所有节点的剩余能量和平均能量等因素来选择通信方式和传输路径。通过MATLAB工具,对提出的算法进行了仿真实验。结果表明,在100 m×100 m的小面积监测区域和200 m×200 m的大面积监测区域内,与LEACH、DEEC、IMP-LEACH算法相比,该算法降低了WSNs中节点的能量消耗,延长了生存周期,同时提高了数据吞吐量。

Comprehensive utilization of complex rubidium ore resources:Mineral dissociation and selective leaching of rubidium and potassium

Currently,the process of extracting rubidium from ores has attracted a great deal of attention due to the increasing application of rubidium in high-technology field.A novel process for the comprehensive utilization of rubidium ore resources is proposed in this paper.The process consists mainly of mineral dissociation,selective leaching,and desilication.The results showed that the stable silicon–oxygen tetrahedral structure of the rubidium ore was completely disrupted by thermal activation and the mineral was completely dissociated,which was conducive to subsequent selective leaching.Under the optimal conditions,extractions of 98.67% Rb and 96.23%K were obtained by leaching the rubidium ore.Moreover,the addition of a certain amount of activated Al(OH)_(3) during leaching can effectively inhibit the leaching of silicon.In the meantime,the leach residue was sodalite,which was successfully synthesized to zeolite A by hydrothermal conversion.The proposed process provided a feasible strategy for the green extraction of rubidium and the sustainable utilization of various resources.

An insight on the mechanism of efficient leaching of vanadium from vanadium shale induced by microwave-generated hot spots

Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscopic morphology analysis and numerical simulation by COMSOL Multiphysics software.The effects of the microwave power,leaching temperature,CaF_(2) dosage,H_(2)SO_(4) concentration,and leaching time on the vanadium recovery were investigated.A vanadium recovery of 80.66%is obtained at a microwave power of 550 W,leaching temperature of 95℃,CaF_(2) dosage of 5wt%,H_(2)SO_(4) concentration of 20vol%,and leaching time of 2.5 h.Compared with conventional leaching technology,the vanadium recovery increases by 6.18%,and the leaching time shortens by 79.17%.More obvious pulverization of shale particles and delamination of mica minerals happen in the microwave-assisted leaching process.Numerical simulation results show that the temperature of vanadium shales increases with an increase in electric field(E-field).The distributions of E-field and temperature among vanadium shale particles are relatively uniform,except for the higher content at the contact position of the particles.The analysis results of scaleup experiments and leaching experiments indicate high-temperature hot spots in the process of microwave-assisted leaching,and the local high temperature destroys the mineral structure and accelerates the reaction rate.

煤矿巷道无线传感器网络的LEACH协议改进

将LEACH协议应用于环境复杂的煤矿巷道中存在不足,为了使LEACH协议更适用于煤矿巷道,对LEACH协议进行改进。首先,本文对选择簇头的阈值函数进行调整,加入节点剩余能量、位置信息以及邻节点数量因素;其次,改进建簇算法,节点通过计算与簇头节点和汇聚节点之间的距离来判断加入簇头还是与汇聚节点直接通信;最后,改进簇间通信机制,簇头之间通过多跳方式进行数据传输,并根据能量和距离信息选择下一跳簇头节点,提高簇间数据传输的可靠性。仿真实验表明,改进后的LEACH协议可以有效降低煤矿巷道无线传感器网络能耗,延长网络生命周期。

Occurrence,leaching behavior,and detoxification of heavy metal Cr in coal gasification slag

Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical heavy metal Cr in CGS is investigated.The leaching behavior of Cr under different conditions is studied in detail.Acid leaching-selective oxidation-coprecipitation method is proposed based on the characteristics of Cr in CGS.The detoxification of Cr in CGS is realized,and the detoxification mechanism is clarified.Results show that Cr is highly enriched in CGS.The speciation of Cr is mainly residual fraction(74.47%-86.12%),which is combined with amorphous aluminosilicate.Cr^(3+)and Cr^(6+)account for 90.93%-94.82%and 5.18%-9.07%of total Cr,respectively.High acid concentration and high liquid-solid ratio are beneficial to destroy the lattice structure of amorphous aluminosilicate,thus improving the leaching efficiency of Cr,which can reach 97.93%under the optimal conditions.Acid leaching-selective oxidation-coprecipitation method can realize the detoxification of Cr in CGS.Under the optimal conditions,the removal rates of Fe^(3+)and Cr^(3+)in the leaching solution are 80.99%-84.79%and 70.58%-71.69%,respectively,while the loss rate of Al^(3+)is only 1.10%-3.35%.Detoxification slag exists in the form of Fe-Cr coprecipitation(Fe_(1-x)Cr_xOOH),which can be used for smelting.The detoxification acid leaching solution can be used to prepare inorganic polymer composite coagulant poly-aluminum chloride(PAC).This study can provide theoretical and data guidance for detoxification of heavy metal Cr in CGS and achieve resource utilization of coal gasification solid waste.

Recovery of Li_(2)CO_(3)and FePO_(4)from spent LiFePO_(4)by coupling technics of isomorphic substitution leaching and solvent extraction

Efficient and low-cost recycling of spent lithium iron phosphate(LiFePO_(4),LFP)batteries has become an inevitable trend.In this study,an integrated closed-loop recycling strategy including isomorphic substitution leaching and solvent extraction process for spent LFP was proposed.An inexpensive FeCl_(3)was used as leaching agent to directly substitute Fe^(2+)from LFP.99%of Li can be rapidly leached in just 30 min,accompanied by 98%of FePO_(4)precipitated in lixivium.The tri-n-butyl phosphate(TBP)-sulfonated kerosene(SK)system was applied to extract Li from lixivium through a twelve-stage countercurrent process containing synchronous extraction and stepwise stripping of Li^(+)and Fe^(3+).80.81%of Li can be selectively enriched in stripping liquor containing 3.059 mol·L^(-1)of Li^(+)under optimal conditions.And the Fe stripping liquor was recovered for LFP re-leaching,of which,Fe^(2+)was oxidized to Fe^(3+)by appropriate H_(2)O_(2).Raffinate and lixivium were concentrated and entered into extraction process to accomplished closeloop recycling process.Overall,the results suggest that more than 99%of Li was recovered.FeCl_(3)holding in solution was directly regenerated without any pollutant emission.The sustainable mothed would be an alternative candidate for total element recycling of spent LFP batteries with industrial potential.

基于能量均衡高效的LEACH改进算法

LEACH路由协议是无线传感器网络一个经典的分簇路由方法,但在限能严重的无线网络中,节点功耗高、生存时间短等问题严重影响网络性能,为此提出了改进的基于能量均衡高效的LEACH-X协议。通过加入最优簇首数,提出修正的剩余能量因子,考虑节点的剩余能量、周期内当选过簇首的次数以及密度因子,并对部署区域分区,针对区域调整距离因子增益参数的权重来修正簇首选举阈值函数;接着进行二次竞争并最终选举簇首,从而减小节点能耗,使WSN存活时间得到一定的延长。仿真结果表明,与传统LEACH协议进行对比,LEACH-X协议降低了网络能耗,延长了网络生存时间。

LEACH与LEACH-C、LEACH-E、LEACH-ED的仿真与比较

笔者详细介绍了簇头的选举是随机的LEACH算法,在选择簇头的过程中,考虑节点的能量消耗情况的LEACH-E算法,基于网络总的能量消耗最小的优化目标,得出所有节点分簇方案的LEACH-C算法以及进一步考虑到节点位置的LEACH-ED算法。仿真后,分别从程序层面介绍了这几种算法的不同之处,分析了基站位置的对LEACH、LEACH-C、LEACH-E以及LEACH-ED的影响。

Reclamation of CO_(2) sodium silicate used sands by steam leaching

The bond film on the surface of the CO_(2) sodium silicate used sands is not easy to decompose,therefore,it is difficult to reclaim used sands.A new reclamation method of CO_(2) sodium silicate used sands was developed by steam leaching,which can reduce the water consumption of reclamation and improve the removal effect of sodium silicate bond film.Firstly,the leaching effect of the sodium silicate sands after 20/200/400/600/800/1,000°C heat preservation treatment was simulated.Furthermore,the influence of the leaching time on the removal effect of the sodium silicate bond film was studied.Finally,the casting properties of the reclaimed sands after the leaching reclamation treatment were tested.The results show for simulated used sands after 30 min of steam leaching,the removal ratio of the alkali exceeds 84.1%,the removal ratio of silicate is 86.2%,and the removal ratio of carbonate is 93.6%.The removal rate of alkali,silicate and carbonate is relatively low in the leaching time of 30-50 min.Considering the reclamation effect and cost,the leaching time is controlled in 30 min.Water consumption is only 60%of the mass of used sands for 30 min steam leaching,while it is 200%for wet reclamation.Morphological analysis shows that most of the hazardous substances in the used sands are removed in 30 min steam leaching,and the reclaimed sands surface after steam leaching in 50 min is as smooth as new sands.After 30 min of steam leaching,the alkali removal effect of the factory used sands can reach 81.5%,the water consumption by the steam leaching reclamation is 58%of the mass of the used sand,which is similar to the result of simulated used sands.The performance of reclaimed sands obtained after 30 min steam leaching is better than that of new sands when the amount of sodium silicate added is 6%of the mass of the reclaimed sands and the CO_(2) blowing time is 15 s:the 24 h ultimate compressive strength of reclaimed sands is 5.6 MPa(equated with new sands),and the collapsibility compressive strength is 5.2 MPa,which is lower than the collapsibility compressive strength of new sands(7.7 MPa).This indicates that the reclamation of CO_(2) sodium silicate used sands by steam leaching is a feasible method.

Fabrication of Porous Polycaprolactone/Carboxymethylcellulose Scaffolds by using Salt Leaching Technique

The purpose of this work was to fabricate three-dimensional porous scaffolds by using the salt leaching technique.This technique is simple and it does not need the pressure or dislike expensive equipment.The study selected polycaprolactone blended with carboxymethylcellulose that is the additive.The ratios of them were derived from mixture design in Minitab program that was 98/2(P1),93.5/6.5(P2),89/11(P3),84.5/15.5(P4),and 80/20(P5),respectively.The scanning electron microscopy(SEM)was applied to assess the physical properties and the pore size dimension of the scaffold from SEM micrographs.The results of SEM present the scaffolds happened interconnected porous structures that are found in all of the P1-P5 samples.The pore size dimension of all sample scaffolds is in the range of 264.11-348.28μm.Whereas the largest and the smallest of pore size are the sample of P3 and P2,respectively,while the porosity ranges from 98.06%-98.88%that the sample of P5 is the greatest and the sample of P4 is the slightly lowest.In conclusion,the blended PCL/CMC scaffolds P1-P5 were formed by salt leaching technique suitable to use in tissue engineering application.However,the amount of CMC blended with PCL should be reasonable in order to adjust the hydrophilic of the scaffold.