Dissolution behavior of mechanical synthetic carbonate mixtures from the system ZnCO3–PbCO3–H2O in aqueous solution at 25 °C

IF 3.1 3区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Applied Geochemistry Pub Date : 2025-04-01 DOI:10.1016/j.apgeochem.2025.106383

Zongqiang Zhu , Chengyou Ma , Xiaoling Yu , Xinghang Liu , Peijie Nong , Fei Luo , Xiaoke Nong , Lihao Zhang , Shen Tang , Zhiqiang Kang , Yinian Zhu

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引用次数: 0

Abstract

Understanding the ZnCO₃–PbCO₃–H₂O system is still a challenge for the thermodynamical modelling due to the different crystal structures of the two endmembers, rhombohedral smithsonite and orthorhombic cerussite. In the present work, a range of Pb-bearing smithsonite, Zn-bearing cerussite and their mixture having the bulk constituent Pb/(Zn + Pb) mole ratio (X_Pb) of 0.000–1.000 had been prepared and dissolved in water at 25 °C for 330 days. For dissolution in initially N₂-degassed water (NW) and CO₂-saturated water (CW), the average log IAPs (ion activity products) at the final stable state (≈log K_sp, solubility product constants) were computed to be −10.71 ± 0.07 ∼ −10.56 ± 0.06 and −10.88 ± 0.23 ∼ −10.89 ± 0.21 for smithsonite, −13.26 ± 0.04 ∼ −13.23 ± 0.08 and −12.72 ± 0.06 ∼ −12.69 ± 0.03 for cerussite, respectively. The incorporation of Pb into smithsonite would slightly increase the log IAPs for the Pb-smithsonite, while very small amount of the Zn incorporation into cerussite would significantly decrease the log IAPs for the Zn-cerussite. The Guggenheim parameters for the smithsonite (R

\overline{3}

c) – cerussite (Pmcn) solid solutions were estimated to be a₀ = 2.79 for the smithsonite-side and a₀ = 2.20 for the cerussite-side from the largest X_Pb in the Pb-smithsonite of 0.094 and the smallest X_Pb in the Zn-cerussite of 0.751. In the Lippmann diagrams for the smithsonite–cerussite–H₂O system, the (Zn_1-xPb_x)CO₃ solids dissolved incongruently, and the aqueous compositions evolved with time upward to the quasi-equilibrium curves for the Pb-smithsonite having a smaller X_Pb, and then along them from right to left, attained and intersected the solutus curve and the saturation curve for pure smithsonite, and finally moved upward to the saturation curve for cerussite. The Pb-poorer water solutions were finally at equilibrium with both the Zn-richer Pb-smithsonite and the Pb-richer Zn-cerussite. The result can offer a deep understanding of the geochemical and environmental behaviors of lead and zinc.

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来源期刊

Applied Geochemistry 地学-地球化学与地球物理

CiteScore

6.10

自引率

8.80%

发文量

272

审稿时长

65 days

期刊介绍： Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application. Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.