现代鱼卵硅酸盐化模拟实验

扬子地台早寒武世和埃迪卡拉纪陡山沱期的地层中发现了大量保存精美的磷酸盐化球状化石,其中一些球状化石为硅化保存,它们为解释早期生命的起源和演化提供了宝贵的素材。在这些球状化石的种属分类和胚胎真伪等方面,不同的研究人员之间还存在较大的分歧。本文通过设计实验,以团头鲂鱼卵为材料,将团头鲂鱼卵注入不同浓度硅酸盐溶液中,观察鱼卵在不同溶液中的保存状态和硅化潜力。研究结果显示:团头鲂鱼卵硅化非常迅速,鱼卵最有利的保存环境是非碱性条件下的还原条件;在同一实验条件下,同一种属,不同形态的鱼卵和鱼卵的不同部分都可以保存下来。上述实验为球状化石的种属分类和真伪鉴定研究提供了有益参考,并为球状化石形成过程的探索提供了线索和思路。

Typical roles of metal ions in mineral flotation:A review

In flotation,metal ions possess significant roles that are usually fulfilled by either selectively activating or depressing the target minerals.Despite that tremendous efforts have been made to address the roles of metal ions in flotation,it still lacks a comprehensive review,especially to compare various ions instead of focusing on a specific one.This review begins by elaborately categorizing the factors involved in affecting the roles of metal ions in flotation.After that,well-accepted mechanisms are updated and discussed from the ore type.Furthermore,typical approaches to explore the underlying mechanisms are emphasized,including traditional techniques such as micro-flotation,contact angle measurement,zeta potential measurement,and other recent prevailing methodologies,like computational method,solution chemistry calculation,and cyclic voltammetry.This work will pave the way to promote flotations via activities like selectively adding/reducing metal ions,choosing reagents,and regulating the slurry chemistry.

Iron Activation of Natural Aluminosilicates to Remove Arsenic from Groundwater

Low-cost adsorbents constituted by Fe-modified-aluminosilicates （laminar and zeolite type minerals） were developed and characterized to be used in the arsenic removal from groundwater. Iron activation was carried out ＂in situ＂ by the synthesis and deposition of mesoporous ferrihydrite. Natural iron-rich aluminosilicate was used as reference. All samples were characterized by X-ray diffraction, Raman spectroscopy, BET N2-adsorption, SEM-EDS microscopy and ICP chemical analysis. Experimental results of arsenic sorption showed that iron-poor raw materials were not active, unlike iron activated samples. The iron loading in all activated samples was below 5% （expressed as Fe203）, whereas the removal capacity of these samples reaches between 200-700 gg of As by g of adsorbent, after reusing between 17 cycles and 70 cycles up to adsorbent saturation. Differences can be associated to mineral structure and to the surface charge modification by iron deposition, affecting the attraction of the As-oxoanion. On the basis of low-cost raw materials, the easy chemical process for activation shows that these materials are potentially attractive for As（V） removal. Likewise, the activation of clay minerals, with natural high content of iron, seems to be a good strategy to enhance the arsenic adsorption ability and consequently the useful life of the adsorbent.

Influence of silicate anions structure on desilication in silicate-bearing sodium aluminate solution

The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivative spectra. The results show that the desilication ratio in the solution prepared by the addition of sodium silicate(solution-SS) is much greater than that in the solution by the addition of green liquor(solution-GL), and low alumina concentration in the sodium aluminate solutions facilitates the desilication process. It is also shown that alumino-silicate anions in the solution-GL, and Q^3 polymeric silicate anions in solution-SS are predominant, respectively. In addition, increasing the concentration of silica favors respectively the formation of the alumino-silicate or the Q^3 silicate anions in the solution-GL or the solution-SS. Therefore, it can be inferred that the low desilication ratio in the silicate-bearing aluminate solution is mainly attributed to the existence of alumino-silicate anions.

Carbon Dioxide Mineralisation and Integration with Flue Gas Desulphurisation Applied to a Modern Coal-Fired Power Plant

For Finland, carbon dioxide mineralisation was identified as the only option for CCS （carbon capture and storage） application. Unfortunately it has not been embraced by the power sector. One interesting source-sink combination, however, is formed by magnesium silicate resources at Vammala, located -85 km east of the 565 MWe coal-fired Meri-Pori Power Plant on the country＇s southwest coast. This paper assesses mineral sequestration of Meri-Pori power plant CO2, using Vammala mineral resources and the mineralisation process under development at Abo Akademi University. That process implies Mg（OH）E production from magnesium silicate-based rock, followed by gas/solid carbonation of the Mg（OH）2 in a pressurised fluidised bed. Reported are results on experimental work, i.e., Mg（OH）2 production, with rock from locations close to Meri-Pori. Results suggest a total CO2 fixation capacity -50 Mt CO2 for the Vammala site, although production of Mg（OH）2 from rock from the site is challenging. Finally, as mineralisation could be directly applied to flue gases without CO2 pre-capture, we report from experimental work on carbonation of Mg（OH）2 with CO2 and CO2-SO2-O2 gas mixtures. Results show that SO2 readily reacts with Mg（OH）2, providing an opportunity to simultaneously capture SO2 and CO2, which could make separate flue gas desulphurisation redundant.