Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification-ca...Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification-carbonation method was developed to recover alkali and alumina from Bayer red mud under mild reaction conditions. Batch experiments were performed to evaluate the potential effects of im- portant parameters such as temperature, amount of CaO added, and CO2 partial pressure on the recovery of alkali and alumina. The results showed that 95.2% alkali and 75.0% alumina were recovered from red mud with decreases in the mass ratios of Na2O to Fe2O3 and of Al2O3 to Fe2O3 from 0.42 and 0.89 to 0.02 and 0.22, respectively. The processed red mud with less than 0.5wt% Na2O can potentially be used as a construction material.展开更多
用沉淀技术对炼油厂的碱渣进行再生处理,考察了影响再生效果的各种因素,结果表明,在沉淀反应温度20℃、反应时间超过30 m in、沉淀剂CuO与Na2S的摩尔比为1.4的条件下,S2-的去除率可达98%以上,沉淀剂CuO再生后可以循环使用,并且再生后碱...用沉淀技术对炼油厂的碱渣进行再生处理,考察了影响再生效果的各种因素,结果表明,在沉淀反应温度20℃、反应时间超过30 m in、沉淀剂CuO与Na2S的摩尔比为1.4的条件下,S2-的去除率可达98%以上,沉淀剂CuO再生后可以循环使用,并且再生后碱液的物理性质与新鲜碱液基本相同。展开更多
Radioactive alkali fluoride salts are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel, and appear in the formof fluidity granule, or powder. In order to prevent the ra...Radioactive alkali fluoride salts are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel, and appear in the formof fluidity granule, or powder. In order to prevent the radionuclides from being released into the environment(especially, via exposure to water), it is necessary to develop a new technology for the temporary storage or final disposal of wastes containing radioactive fluorides. The immobilization of alkali fluoride wastes in phosphate glasses has been proposed. In this study, iron phosphate(IP) glasses and sodium aluminophosphate(NaAlP) glasses were evaluated for the immobilization of simulated radioactive fluoride wastes. IP and NaAlP glass matrixes were mixed with simulated wastes and reacted in air at temperatures in the range of 950–1200°C. A high waste loading was obtained in the experiment. The properties of the waste forms were characterized by X-ray diffraction and Raman spectroscopy. The latter indicated that IP glass contains less Q^2 without Q^3(2 and 3 represent the number of bridging oxygens on a PO_4 tetrahedron), and it is concluded that IP glass is more stable than NaAlP glass. Leaching tests were performed in deionized water by using the product consistency test A(PCT-A method), and the result shows that the leaching resistance of IP waste forms is better than that of NaAlP waste forms. This study demonstrates the potential of IP glass for the stabilization and immobilization of radioactive fluoride wastes from MSRs.展开更多
A Solid Oxide Fuel Cell(SOFC)is an electrochemical device that converts the chemical energy of a substance into electrical energy through an oxidation-reduction mechanism.The electrochemical reaction of a solid oxide ...A Solid Oxide Fuel Cell(SOFC)is an electrochemical device that converts the chemical energy of a substance into electrical energy through an oxidation-reduction mechanism.The electrochemical reaction of a solid oxide fuel cell(SOFC)generates heat,and this heat can be recovered and put to use in a waste heat recovery system.In addition to preheating the fuel and oxidant,producing steam for industrial use,and heating and cooling enclosed rooms,this waste heat can be used for many more productive uses.The large waste heat produced by SOFCs is a worry that must be managed if they are to be adopted as a viable option in the power generation business.In light of these findings,a novel approach to SOFC waste heat recovery is proposed.The SOFC is combined with a“Thermoelectric Generator and an Alkali Metal Thermoelectric Converter(TG-AMTC)”to transform the excess heat generated by both the SOFC and the TG-AMTC.The proposed TG-AMTC is evaluated using a number of performance indicators including power density,operating temperature,heat recovery rate,exergetic efficiency,energy efficiency,and recovery time.The experimental results state that TG-AMTC has provided an exergetic efficiency,energetic efficiency,and recovery time of 97%,98%,and 23%,respectively.The study proves that the proposed TG-AMTC for SOFC is an efficient method of recovering waste heat.展开更多
Chromium released during municipal solid waste incineration(MSWI)is toxic and carcinogenic.The removal of chromium from simulated MSWI flue gas by four sorbents(CaO,bamboo charcoal(BC),powdered activated carbon(PAC),a...Chromium released during municipal solid waste incineration(MSWI)is toxic and carcinogenic.The removal of chromium from simulated MSWI flue gas by four sorbents(CaO,bamboo charcoal(BC),powdered activated carbon(PAC),and Al_(2)O_(3))and the effects of four oxides(SiO_(2),Al_(2)O_(3),Fe_(2)O_(3),and CaO)on chromium speciation transformationwere investigated.The results showed that the removal rates of total Cr by the four sorbents were Al_(2)O_(3)<CaO<PAC<BC,while the removal rates of Cr(Ⅵ)by the four sorbents were Al_(2)O_(3)<PAC<BC<CaO.CaO had a strong oxidizing effect on Cr(Ⅲ),while BC and PAC had a better-reducing effect on Cr(Ⅵ).SiO_(2)was better for the reduction of Na_(2)CrO_(4)and K_(2)CrO_(4)above 1000℃due to its strong acidity,and the addition of CaO significantly inhibited the reduction of Cr(Ⅵ).MgCrO_(4)decomposed above 700℃to form MgCr_(2)O_(4),and the reaction between MgCrO_(4)and oxides also existed in the form of a more stable trivalent spinel.Furthermore,when investigating the effect of oxides on the oxidation of Cr(Ⅲ)in CrC_(l3),it was discovered that CaO promoted the conversion of Cr(Ⅲ)to Cr(Ⅵ),while the presence of chlorine caused chromium to exist in the form of Cr(V),and increasing the content of CaO and extending the heating time facilitated the oxidation of Cr(Ⅲ).In addition,silicate,aluminate,and ferrite were generated after the addition of SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),which reduced the alkalinity of CaO and had an important role in inhibiting the oxidation of Cr(Ⅲ).The acidic oxides can not only promote the reduction of Cr(Ⅵ)but also have an inhibitory effect on the oxidation of Cr(Ⅲ)ascribed to alkali metals/alkaline earth metals,and the proportion of acidic oxides can be increased moderately to reduce the generation of harmful substances in the hazardous solid waste heat treatment.展开更多
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(No.U1202274)the National Natural Science Foundation of China(No.51204040)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China(No.20120042110011)the Fundamental Research Funds for the Central Universities(No.N140204015)
文摘Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification-carbonation method was developed to recover alkali and alumina from Bayer red mud under mild reaction conditions. Batch experiments were performed to evaluate the potential effects of im- portant parameters such as temperature, amount of CaO added, and CO2 partial pressure on the recovery of alkali and alumina. The results showed that 95.2% alkali and 75.0% alumina were recovered from red mud with decreases in the mass ratios of Na2O to Fe2O3 and of Al2O3 to Fe2O3 from 0.42 and 0.89 to 0.02 and 0.22, respectively. The processed red mud with less than 0.5wt% Na2O can potentially be used as a construction material.
基金supported by the“Strategic Priority Research Program”of the Chinese Academy of Sciences(XD02005003)
文摘Radioactive alkali fluoride salts are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel, and appear in the formof fluidity granule, or powder. In order to prevent the radionuclides from being released into the environment(especially, via exposure to water), it is necessary to develop a new technology for the temporary storage or final disposal of wastes containing radioactive fluorides. The immobilization of alkali fluoride wastes in phosphate glasses has been proposed. In this study, iron phosphate(IP) glasses and sodium aluminophosphate(NaAlP) glasses were evaluated for the immobilization of simulated radioactive fluoride wastes. IP and NaAlP glass matrixes were mixed with simulated wastes and reacted in air at temperatures in the range of 950–1200°C. A high waste loading was obtained in the experiment. The properties of the waste forms were characterized by X-ray diffraction and Raman spectroscopy. The latter indicated that IP glass contains less Q^2 without Q^3(2 and 3 represent the number of bridging oxygens on a PO_4 tetrahedron), and it is concluded that IP glass is more stable than NaAlP glass. Leaching tests were performed in deionized water by using the product consistency test A(PCT-A method), and the result shows that the leaching resistance of IP waste forms is better than that of NaAlP waste forms. This study demonstrates the potential of IP glass for the stabilization and immobilization of radioactive fluoride wastes from MSRs.
基金Foundation of Heilongjiang Bayi Agricultural University(Grant Nos.ZRCPY201916ZRCPY201817).
文摘A Solid Oxide Fuel Cell(SOFC)is an electrochemical device that converts the chemical energy of a substance into electrical energy through an oxidation-reduction mechanism.The electrochemical reaction of a solid oxide fuel cell(SOFC)generates heat,and this heat can be recovered and put to use in a waste heat recovery system.In addition to preheating the fuel and oxidant,producing steam for industrial use,and heating and cooling enclosed rooms,this waste heat can be used for many more productive uses.The large waste heat produced by SOFCs is a worry that must be managed if they are to be adopted as a viable option in the power generation business.In light of these findings,a novel approach to SOFC waste heat recovery is proposed.The SOFC is combined with a“Thermoelectric Generator and an Alkali Metal Thermoelectric Converter(TG-AMTC)”to transform the excess heat generated by both the SOFC and the TG-AMTC.The proposed TG-AMTC is evaluated using a number of performance indicators including power density,operating temperature,heat recovery rate,exergetic efficiency,energy efficiency,and recovery time.The experimental results state that TG-AMTC has provided an exergetic efficiency,energetic efficiency,and recovery time of 97%,98%,and 23%,respectively.The study proves that the proposed TG-AMTC for SOFC is an efficient method of recovering waste heat.
基金supported by the National R&D Program Project of China(No.2019YFC1907000)the Key Research and Development Program of Hubei Province(No.2020BCA076)+1 种基金the Natural Sciences Foundation of China(No.52176127)Natural Science Foundation of Hubei Province(No.2022CFB045)。
文摘Chromium released during municipal solid waste incineration(MSWI)is toxic and carcinogenic.The removal of chromium from simulated MSWI flue gas by four sorbents(CaO,bamboo charcoal(BC),powdered activated carbon(PAC),and Al_(2)O_(3))and the effects of four oxides(SiO_(2),Al_(2)O_(3),Fe_(2)O_(3),and CaO)on chromium speciation transformationwere investigated.The results showed that the removal rates of total Cr by the four sorbents were Al_(2)O_(3)<CaO<PAC<BC,while the removal rates of Cr(Ⅵ)by the four sorbents were Al_(2)O_(3)<PAC<BC<CaO.CaO had a strong oxidizing effect on Cr(Ⅲ),while BC and PAC had a better-reducing effect on Cr(Ⅵ).SiO_(2)was better for the reduction of Na_(2)CrO_(4)and K_(2)CrO_(4)above 1000℃due to its strong acidity,and the addition of CaO significantly inhibited the reduction of Cr(Ⅵ).MgCrO_(4)decomposed above 700℃to form MgCr_(2)O_(4),and the reaction between MgCrO_(4)and oxides also existed in the form of a more stable trivalent spinel.Furthermore,when investigating the effect of oxides on the oxidation of Cr(Ⅲ)in CrC_(l3),it was discovered that CaO promoted the conversion of Cr(Ⅲ)to Cr(Ⅵ),while the presence of chlorine caused chromium to exist in the form of Cr(V),and increasing the content of CaO and extending the heating time facilitated the oxidation of Cr(Ⅲ).In addition,silicate,aluminate,and ferrite were generated after the addition of SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),which reduced the alkalinity of CaO and had an important role in inhibiting the oxidation of Cr(Ⅲ).The acidic oxides can not only promote the reduction of Cr(Ⅵ)but also have an inhibitory effect on the oxidation of Cr(Ⅲ)ascribed to alkali metals/alkaline earth metals,and the proportion of acidic oxides can be increased moderately to reduce the generation of harmful substances in the hazardous solid waste heat treatment.
