SEPARATION AND PURIFICATION TECHNOLOGY
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2022
·
IF 9.136
Yu Yong,Hu Jianhang,Li Yongkui,Zhong Dapeng,Wang Hua
Arsenic ( As ) -bearing gypsum sludge, one of the biggest As-bearing wastes, has seriously threatened ecological security due to the great mobility and leaching toxicity of As. Unfortunately, most of this sludge was discharged into tailing ponds without treatment. In this paper, a novel co-process of As-bearing gypsum sludge, waste carbon cathode (WCC) and Fe powder for simultaneous separation and solidification of As is proposed via reduction-magnetic separation. In the reduction process, Ca 3 (AsO 4 ) 2 was reduced and then enriched to α-Fe (Fe-As solid solution), and the As solidification ratio reached 90.5%. Meanwhile, NaF in waste carbon cathodes was transformed into CaF 2 and NaCa 2 FSiO 4 . The As and F leached content were only 0.053 mg/L and 3.10 mg/L, when evaluated using the toxicity characteristic leaching procedure. After magnetic separation, α-Fe (magnetic phase) was separated and recovered, and the weight and volume losses of As-bearing waste were 70% and 60%, respectively, compared with the raw material. The As residual content in the non-magnetic phase met the standard of solid waste (As < 0.1 wt%), which acted as a flux during the smelting process, minimizing the environmental risk and realizing resource recycling. Moreover, waste carbon cathodes can be reused as fuel and as a reducing agent, which significantly reduces production costs. This proposed technique reduces hazardous waste, is more effective, and is also more economical.
研究领域:
环境科学
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材料科学
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DOI
高影响因子
Environmental Earth Sciences
·
2022
·Vol. 81
·期 21
·1-19
·
IF 3.119
An Xiaoyu,Zuo Dianjun,Wang Fei,Liang Chao
The cement solidification/stabilization method of heavy metal contaminated soils has been promoted in engineering practice and applied on a large scale for site remediation, but it still reveals some scientific problems in the current complex and variable global extreme climate. To solve these problems, this study used waste soda residue as a composite additive, and established an innovative composite model (cement-soda) to remediate lead-contaminated soil. The innovative composite model for unconfined compressive strength (UCS) and toxic leaching properties under different conditions were investigated As well as curing and leaching mechanisms are discussed, and future industrial practice was evaluated. The results showed that the addition of soda residue improved the early (20 days) UCS of the composite curing agent for lead-contaminated soil by an average of 23.1% MPa. The UCS strength was 0.96 MPa, which was the maximum when the percentage of soda residue composite was 40%. The concentration of Pb 2+ in the leachate of the cement-soda residue (CSH) composite curing agent was greatly reduced (average 3.28 times) compared with that of a single cement in the same situation, with an average leached Pb 2+ concentration of 1.87 mg·L −1 . This finding indicates that the addition of alkali residue improved the curing effect. The curing mechanism was divided into four steps, mainly a complex physicochemical reaction between the CSH composite and soil particles. The leaching mechanism of CSH to aqueous solution is mainly the consumption of acid ions by alkaline substances. Collectively, this study will provide scientific data to support potential lead-containing soil in site remediation technologies and future large-scale engineering applications.
研究领域:
环境科学
·
土壤修复
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Dongping Song,Tao Huang,Kai Chen,Jialin Cui,Qingyang Xu,Chengyu Yan,Chengzhe Yang,Shaohang Wan,Minfeng Tao
In this study, the magnesium phosphate cement (MPC) coupling with graphene nanosheets (GNP) was employed to solidify municipal solid waste incineration fly ashes (MSWI-FA) and stabilize the contaminants of heavy metals (HMs) and chloride salts in the matrix. The maximum compressive strength of 45.62 MPa and the minimum leaching concentration of 0.012, 0.0064, 0.00079, 0.0045, and 0.048 mg/L for Zn, Cu, Cd, Pb, and total Cr and 0.86 g/L for chloride were obtained from the GNP-MPC-MSWI-FA-cemented matrix in the orthogonal tests and toxicity-leaching experiments, respectively. MSWI-FA significantly changed the MPC hydration process. The influence of MPC on the speciation transformation of HMs was more prominent than that of GNP. Fick's theory model was appropriate in fitting the whole leaching process of HMs and dissolvable chloride species from the matrix under acid-immersion conditions. Both K-struvite and Phase-5 were formed in the matrix in mineral analysis, verifying the formation of both MPC and magnesium oxychloride cement (MOC). The chloride salts in the MSWI-FA facilitated the self-cementation of MOC from light-burnt magnesia in MPC. The mechanisms including the formation of phosphate precipitation, gelation encapsulation, and chemical hydration brought by MPC attributed to effective solidification/stabilization of HMs and chloride in the MSWI-FA.
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产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2023
·Vol. 31
·期 5
·6929-6943
·
IF 5.8
Li Jinlin,Sun Chunbao,Wang Peilong,Kou Jue
For over two hundred years, cyanide has served as the primary reagent for gold extraction. However, due to its high toxicity, the use of cyanide poses significant risks. Traditional low-toxicity leaching reagents have limitations that restrict their widespread industrial application, leading to the necessity for the development of new, efficient, and low-toxic gold leaching reagents to support sustainable gold production. In this study, a novel, efficient, and low-toxicity gold extraction reagent was synthesized at high temperatures by combining urea, sodium carbonate, and a specific iron salt. The research delved into the leaching ability of the reagent under different synthesis conditions and examined the generation of free cyanide content as a by-product. Findings indicated that reagents synthesized with either potassium ferrocyanide or potassium ferricyanide displayed comparable leaching capabilities. Reagents synthesized at 800 °C exhibited lower levels of free cyanide ions and reduced toxicity. Additionally, this reagent demonstrated exceptional selectivity for gold, while in minimal dissolution of copper, iron, nickel, lead, and iron from computer central processing unit (CPU) pins. Under optimal conditions, the efficiency of gold extraction from CPU pins reached 94.65%. Hence, this reagent holds significant potential for the low-toxicity extraction of gold from electronic waste or auriferous concentrates.
研究领域:
冶金学
·
环境科学
·
材料科学
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化学工程
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废弃物回收
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DOI
高影响因子
危险品化学品经营许可证（带存储）