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leaching behavior and Mechanism of Cement Solidified Heavy Metal Pb in Acid Medium

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Journal of Wuhan University of Technology(Materials Science) 2015年第4期30卷 781-786页

作者：周明凯王彩萍 CHEN Yan CHEN Xiao State Key Laboratory of Silicate Materials for Architectures Wuhan University of Technology

The relationship between Pb leaching concentration and the solution＇s pH with time was analyzed when cement in its solidified form was leached in an acid medium. The effects of the particle size of the solidified form, the cement adding method, and the hydration degree on Pb solidification were also investigated. The experimental results indicate that cement is quickly dissolved and hydrated in the acid medium, forming a C-S-H gel or silicic acid sol with good adsorption. When cement-Pb solidified form is leached in an acetate solution, the hydrated product erodes with time, so the Pb concentration increases slightly in the beginning. Then, some of the Pb ions are absorbed by the newly generated silicic acid sol, C-S-H. Others produce Pb（OH）2 precipitation for secondary solidification, leading to a gradual decrease in the Pb concentration in a leaching time of more than two hours. Moreover, the particle size of the solidified form has important effects on the Pb dissolution. When the amount of added cement is low, with a pH of less than 9.5, the solidification affects the sequence of the original cement powder, the cement hydrated powder, and the cement- Pb solidified form. When the added amount of cement increases with a pH of more than 11, the effect of adding methods on solidification decreases, and the solidified form is a little better than others.

关键词： cement acid medium heavy metal leaching behavior

Characteristics of the stabilized/solidified municipal solid wastes incineration fly ash and the leaching behavior of Cr and Pb

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Frontiers of Environmental Science & Engineering 2016年第1期10卷 192-200页

作者： Yan SHAO Haobo HOU Guangxing WANG Sha WAN Min ZHOU School of Resource and Environment Science Wuhan University Wuhan 430072 China GNSS Research Center Wuhan University Wuhan 430072 China

Fly ash is a hazardous byproduct of municipal solid wastes incineration （MSWI）. An alkali activated blast fumace slag-based cementifious material was used to stabilize/solidify the fly ash at experimental level. The characteristics of the stabilized/solidified fly ash, including metal leachability, mineralogical characteristics and the distributions of metals in matrices, were tested by toxic characteristic leaching procedure （TCLP）, X-ray diffrac- tion （XRD） and scanning electron microscopy-energy dispersive spectrometer （SEM-EDS） respectively. Contin- uous acid extraction was utilized to extract metal ions and characterize their leaching behavior. The stabilization/ solidification procedure for MSWI fly ash demonstrates a strong fixing capacity for the metals by the formation of C- S-H phase, hydrated calcium aluminosilicate and ettringite. The stabilized/solidified fly ash shows a dense and homogeneous microstructure. Cr is mainly solidified in hydrated calcium aluminosilicate, C-S-H and ettringite phase through physical encapsulation, precipitation, adsorption or substitution mechanisms, and Pb is mainly solidified in C-S-H phase and absorbed in the Si-O structure.

关键词： municipal solid waste incineration (MSWI)fly ash blast furnace slag leaching behavior Cr Pb

leaching behavior of metals from high-arsenic dust by NaOH-Na_2S alkaline leaching

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Transactions of Nonferrous Metals Society of China 2016年第2期26卷 575-580页

作者：郭学益易宇石靖田庆华中南大学冶金与环境学院长沙410083 中南大学中国有色金属工业清洁冶金工程研究中心长沙410083

Arsenic is selectively extracted from high-arsenic dust by NaOH-Na2S alkaline leaching process. In the leaching arsenic process, the effects of alkali-to-dust ratio, sodium sulfide addition, leaching temperature, leaching time and liquid-to-solid ratio on metals leaching efficiencies were investigated. The results show that the arsenic can be effectively separated from other metals under the optimum conditions of alkali/dust mass ratio of 0.5, sodium sulfide addition of 0.25 g/g, leaching temperature of 90 ℃, leaching time of 2 h, and liquid-to-solid ratio of 5：1 （mL/g）. Under these conditions, the average leaching efficiencies of arsenic, antimony, lead, tin and zinc are 92.75%, 11.68%, 0.31%, 29.75% and 36.85%, respectively. The NaOH-Na2S alkaline leaching process provides a simple and highly efficient way to remove arsenic from high-arsenic dust, leaving residue as a suitable lead resource.

关键词： high arsenic dust alkaline leaching leaching behavior arsenic

leaching behavior of zinc from crude zinc oxide dust in ammonia leaching

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Journal of Central South University 2021年第9期28卷 2711-2723页

作者： JIANG Tao MENG Fei-yu GAO Wei ZENG Yan SU Huan-huan LI Qian XU Bin YANG Yong-bin ZHONG Qiang School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Pelletizing Plant of Panzhihua Gangcheng Group Co. Ltd.Panzhihua 617000China

Zinc extraction from crude zinc oxide(CZO)is beneficial to the full utilization of secondary resources and environmental *** this paper,a systematic investigation was carried out to study the leaching behavior of CZO by using ammonia-ammonium carbonate *** was found that the maximum leaching rate of zinc from CZO dust was 95.7%under the conditions of[Zn]T:[NH 3]T:[CO_(3)^(2−)]=1:7.00:1.75,liquid to solid ratio 5:1,leaching temperature 30℃ and leaching time 60 *** with pure zinc oxide(PZO)leaching,the CZO leaching required longer time and more leaching agents,which is caused by the Cd^(2+),Pb^(2+) and other metal cationic impurities in *** metal cationic impurities dissolved in the leaching solution and combined with ammonium to form complexes,consuming leaching agents and affecting zinc leaching.

关键词： crude zinc oxide dust ammonia leaching leaching behavior metal cationic impurities

leaching behavior of metals from limonitic laterite ore by high pressure acid leaching

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Transactions of Nonferrous Metals Society of China 2011年第1期21卷 191-195页

作者：郭学益石文堂李栋田庆华中南大学冶金科学与工程学院长沙410083

The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and *** effects of sulfuric acid added,leaching temperature,leaching time and liquid/solid（L/S） ratio on metals extraction were *** than 97% Ni,96% Co,93% Mn,95% Mg and less than 1% Fe are extracted under optimum *** of the high pressure acid leaching residue by chemical and XRD analysis indicates that the residual iron and sulfur are mainly present in phases of hematite and alunite,*** high pressure leaching process provides a simple and efficient way for the high recovery of nickel and cobalt from laterite ore,leaving residue as a suitable iron resource.

关键词： high pressure acid leaching limonitic laterite leaching behavior nickel

Atmospheric oxygen-rich direct leaching behavior of zinc sulphide concentrate

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Transactions of Nonferrous Metals Society of China 2013年第12期23卷 3780-3787页

作者：徐志峰江庆政王成彦江西理工大学冶金与化学工程学院赣州341000 北京矿冶研究总院北京100160

The leaching behavior of main metallic sulphides in zinc concentrate under atmospheric oxygen-rich direct leaching conditions was studied through mineralogical analysis. The results show that the sulphides dissolve obviously except pyrite. Based on the relationship between elemental sulfur and the residual sulphides in the leaching residue, the dissolution of sphalerite, chalcopyrite, covellite and galena is assumed to follow the indirect oxidation reactions, where the acidic dissolution takes place firstly and then the released H2S transfers from the mineral surface into bulk solution and is further oxidized into elemental sulfur. The interface chemical reaction is further supposed as the controlling step in the leaching of these sulphides. The direct electrochemical oxidation reactions are assumed to contribute to the dissolution of pyrrhotite, which is controlled by the diffusion through elemental sulfur layer.

关键词： zinc sulphide concentrate atmospheric direct leaching oxygen-rich leaching leaching behavior mineralogy

Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue

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Transactions of Nonferrous Metals Society of China 2018年第10期28卷 2125-2134页

作者： Yi-wei LI Jun JIANG Sheng-guo XUE Graeme J.MILLAR Xiang-feng KONG Xiao-fei LI Meng LI Chu-xuan LI School of Metallurgy and Environment Central South UniversityChangsha 410083China Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution Central South UniversityChangsha 410083China Institute for Future Environments Science and Engineering FacultyQueensland University of Technology(QUT)Brisbane Qld 4000Australia

This study focused on leaching behavior of alkaline anion and sodium in bauxite residue through ammonium chloride *** results showed that the pH of bauxite residue decreased from 10.49 to 8.93,total alkaline anion(HCO3^-,CO3^2-,OH^-,AlO2^-)concentration reduced from 38.89 to 25.50 mmol/L,leaching rate of soluble sodium was 80.86%with ammonium chloride addition of 0.75%,liquid/solid(L/S)ratio of 3(mL/g),temperature of 30°C and reaction time of 18 h;L/S ratio was the main factor affecting the removal of alkaline anion and the leaching of ***,ammonium chloride promoted the dissolution of diaspore and changed the micro/morphological characteristics with the increase of massive *** findings of this work will contribute to achieve soil-formation of bauxite residue.

关键词： bauxite residue ammonium chloride leaching behavior alkaline regulation soil formation

Effect of temperature on leaching behavior of copper minerals with different occurrence states in complex copper oxide ores

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Transactions of Nonferrous Metals Society of China 2019年第10期29卷 2192-2201页

作者： Gai-rong WANG Yuan-yuan LIU Lin-lin TONG Zhe-nan JIN Guo-bao CHEN Hong-ying YANG Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education) Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China CNMC Luanshya Copper Mines Plc (CLM) Independence AvenueLuanshya City90456Zambia

The effect of temperature on leaching behavior of copper minerals with different occurrence states in complex copper oxide ores was carried out by phase analysis means of XRD, optical microscopy and SEM-EDS. The results indicated that at ambient temperature, the easily leached copper oxide minerals were completely dissolved, while the bonded copper minerals were insoluble. At lukewarm temperature of 40℃, it was mainly the dissolution of copper in isomorphism state. With increasing temperature to 60℃, the copper leaching rate in the adsorbed state was significantly accelerated. In addition, when the temperature increased to 80℃, the isomorphic copper was completely leached, leaving 11.2% adsorbed copper un-leached. However, the copper in feldspar-quartz-copper-iron colloid state was not dissolved throughout the leaching process. Overall, the leaching rates of copper in different copper minerals decreased in the order: malachite, pseudo-malachite > chrysocolla > copper-bearing chlorite > copper-bearing muscovite > copper-bearing biotite > copper-bearing limonite > feldspar-quartz-copper-iron colloid.

关键词： complex copper oxide ores occurrence state temperature leaching behavior copper minerals

Kinetics and leaching behaviors of aluminum from pharmaceutical blisters in sodium hydroxide solution

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Journal of Central South University 2015年第12期22卷 4545-4550页

作者：王重庆王晖顾帼华符剑刚刘又年 School of Chemistry and Chemical Engineering Central South University School of Minerals Processing and Bioengineering Central South University

A hydrometallurgical process was developed for recycling pharmaceutical *** aluminum from pharmaceutical blisters using sodium hydroxide(NaOH) solutions was investigated with respect to leaching behaviors and ***9(34) orthogonal design of experiments suggests that the most significant factor is NaOH concentration followed by temperature and leaching *** experiments demonstrate that the leaching rate of aluminum increases with increasing of the *** optimum conditions are temperature of 70 °C,leaching time of 20 min,NaOH concentration of 1.25 mol/L,liquid-to-solid mass ratio of 15:1 and agitation speed of 400 r/*** optimum conditions,the leaching rate is up to 100%,implying that aluminum and polyvinyl chloride(PVC) plastic in pharmaceutical blisters are separated *** of leaching aluminum is best described by the product layer diffusion control model,and the activation energy is calculated to be 19.26 kJ/mol.

关键词： aluminum kinetics leaching behavior pharmaceutical blisters sodium hydroxide