H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to char...H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to characterize the composition, mineral phase component and microstructure of the titanium slag. The H3PO4 oxidation thermodynamic, mineral phase transformation, microstructure, element distribution in titanium slag during H3PO4 oxidation process and leaching process were investigated. The thermodynamic analysis indicated that H3PO4 could promote the decomposition of MgTi2O5 and CaSiO3. The results indicated that H3PO4 could effectively promote the transformation of titanium-bearing mineral to rutile and enrich the impurities in MxTi（3-x）O5 into phosphate which could be removed by acid leaching process. Under the studied conditions, the leaching rates of magnesium and calcium reached 94.68% and 87.19%, respectively. The acid leached slag containing 0.19% MgO and 0.13% CaO（mass fraction） was obtained.展开更多
The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration...The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca（HzPO4）2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient （Kn） increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg（OH）z＇MgCIz＇8H20 in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.展开更多
In the extraction method for preparing KH2PO4, one of the key processes is the selective extraction of HCI over H3PO4. In our work, extraction kinetic studies have been carried out in a microfluidic device with a coax...In the extraction method for preparing KH2PO4, one of the key processes is the selective extraction of HCI over H3PO4. In our work, extraction kinetic studies have been carried out in a microfluidic device with a coaxial microchannel, using the extractant of 33.3% （by volume） trioctylamine （TOA） dissolved in n-octanol, with differ- ent aqueous phases： the HCI solution, the H3P04 solution, and H3PO4 and KCI solutions of different concentra- tions. The changes of the extraction efficiency of HC1 and H3P04 and the selectivity for HC1 along with the residence time were investigated. We found that fast extraction kinetics could be realized in microfluidic devices, and that HC1 could be extracted faster than H3P04 due to smaller mass transfer resistance and much stronger re- action between HCI and TOA. For the extraction of H3PO4 and KC1 solutions, the selectivity for HC1 first increased and then decreased when TOA was in excess of H3PO4 in the initial feeds, and in contrast, always increased when H3PO4 was in excess of TOA in the initial feeds. The diverse changes of selectivity for HCI along with the residence time indicate that a dynamic control of selectivity in microfluidic devices may be important and accessible for im- proving the KH2P04 conversion efficiency in extraction method.展开更多
文摘H3PO4 oxidation roasting followed by HCl acid leaching was proposed to remove magnesium and calcium from electric furnace titanium slag containing 3.12% MgO and 0.86% CaO. XRF, XRD and SEM techniques were used to characterize the composition, mineral phase component and microstructure of the titanium slag. The H3PO4 oxidation thermodynamic, mineral phase transformation, microstructure, element distribution in titanium slag during H3PO4 oxidation process and leaching process were investigated. The thermodynamic analysis indicated that H3PO4 could promote the decomposition of MgTi2O5 and CaSiO3. The results indicated that H3PO4 could effectively promote the transformation of titanium-bearing mineral to rutile and enrich the impurities in MxTi（3-x）O5 into phosphate which could be removed by acid leaching process. Under the studied conditions, the leaching rates of magnesium and calcium reached 94.68% and 87.19%, respectively. The acid leached slag containing 0.19% MgO and 0.13% CaO（mass fraction） was obtained.
基金Project(B0210)supported by One Hundred Talent Project of Chinese Academy of SciencesProject(2008-G-158)supported by Science and Technology Tackling Key Program of Qinghai Province,China
文摘The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca（HzPO4）2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient （Kn） increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg（OH）z＇MgCIz＇8H20 in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.
基金Supported by the National Natural Science Foundation of China(91334201)
文摘In the extraction method for preparing KH2PO4, one of the key processes is the selective extraction of HCI over H3PO4. In our work, extraction kinetic studies have been carried out in a microfluidic device with a coaxial microchannel, using the extractant of 33.3% （by volume） trioctylamine （TOA） dissolved in n-octanol, with differ- ent aqueous phases： the HCI solution, the H3P04 solution, and H3PO4 and KCI solutions of different concentra- tions. The changes of the extraction efficiency of HC1 and H3P04 and the selectivity for HC1 along with the residence time were investigated. We found that fast extraction kinetics could be realized in microfluidic devices, and that HC1 could be extracted faster than H3P04 due to smaller mass transfer resistance and much stronger re- action between HCI and TOA. For the extraction of H3PO4 and KC1 solutions, the selectivity for HC1 first increased and then decreased when TOA was in excess of H3PO4 in the initial feeds, and in contrast, always increased when H3PO4 was in excess of TOA in the initial feeds. The diverse changes of selectivity for HCI along with the residence time indicate that a dynamic control of selectivity in microfluidic devices may be important and accessible for im- proving the KH2P04 conversion efficiency in extraction method.
