In order to realize resource utilization of industrial tungsten residue and treatment of heavy metal wastewater in mining and metallurgical area of south China,a novel ceramsite was prepared with the main raw material...In order to realize resource utilization of industrial tungsten residue and treatment of heavy metal wastewater in mining and metallurgical area of south China,a novel ceramsite was prepared with the main raw materials of diatomite and tungsten residue.The adsorption behavior of copper ions in solution on the ceramsite was investigated.Results indicated that the surface of the newly-developed ceramsite was rough and porous.There were lots of pores across the ceramsite from inner to outside.MnFe2O4 was one of the main components of the ceramsite.The Cu^2＋adsorption capacity by the ceramsite reached 9.421 mg/g with copper removal efficiency of 94.21%at 303 K,initial Cu^2＋concentration of 100 mg/L and dosage of 0.5 g after 300 min adsorption.With increase of ceramsite dosage,the total adsorption amount of Cu^2＋increased,but the adsorption capacity decreased.The adsorption capacity increased with the increase of solution p H.The isothermal adsorption of Cu^2＋by the ceramsite fitted the Freundlich model better.The adsorption mainly occurred on a heterogeneous surface,and was a favorable process.The adsorption process closely followed the pseudo-second kinetic equation.In initial stage of wastewater treatment,the adsorption process should be controlled mainly by diffusion,and the removal of Cu^2＋can be improved by enhancing agitation.展开更多
Keyhole gas tungsten arc welding(K-TIG)of Q345 low alloy steel plates was simulated by using SYSWELD software.The temperature field of the K-TIG welding process was simulated with three different combined heat sources...Keyhole gas tungsten arc welding(K-TIG)of Q345 low alloy steel plates was simulated by using SYSWELD software.The temperature field of the K-TIG welding process was simulated with three different combined heat sources and was compared with the weld profile that was obtained experimentally.The temperature field that was obtained by a combination of a double ellipsoid heat source on the upper half and a three-dimensional Gauss heat source on the lower half was similar to the real situation.The effects of plate thickness,gap and welding speed on the deformation and stress of the K-TIG welded joints were investigated by K-TIG welding numerical simulation.A reduction in the thickness of the weld plates reduced the z-direction deformation and transverse residual stress;an appropriate gap reduced the residual stress and an increase in the welding speed reduced deformation after welding,but did not help to control the residual stress after welding.展开更多
The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element(FE) method. After the continuous rolling, the gr...The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element(FE) method. After the continuous rolling, the grains of the tungsten rod were refined, and the microhardness was improved; however, a ring region of abnormal grain growth was present at a distance of about 3/5 R(R is the radius of the rod) from the center of the cross section. FE modeling results showed that the equivalent residual strains were minimum around the region of abnormal grain growth; this was due to the release of strain energy by severe plastic deformation, leading a situation where the migration force of grain boundaries was higher than the pinning force of potassium bubbles. By decreasing the initial rolling temperature and rolling speeds, the inhomogeneity of the equivalent residual stain decreased, improving the microstructure uniformity of the doped tungsten.展开更多
The first step in the production of tungsten is to enrich tungsten from two minerals wolframite((Fe,Mn)WO_(4))and scheelite(CaWO_(4))through the leaching process.The leaching residue usually contains a certain amount(...The first step in the production of tungsten is to enrich tungsten from two minerals wolframite((Fe,Mn)WO_(4))and scheelite(CaWO_(4))through the leaching process.The leaching residue usually contains a certain amount(2-5 wt%)of WO_(3) which is higher than that in the tungsten ore(generally less than 1 wt%).In addition,the leaching residue may also consist of other valuable elements such as Cu,Ta,Nb,Sn,Sc,Mn and Fe.Understanding the phases and their compositions present in the residue is one of the key steps for the efficient utilization.The typical residue sample is carefully analysed by electron probe X-ray microanalysis and X-ray fluorescence.A high-temperature process,which includes pre-reduction at 1000-1100℃and smelting reduction at 1450-1500℃,is proposed to efficiently recover the valuable elements.Experimental work and thermo-dynamic calculations confirmed that most of the valuable elements can be economically recovered with optimum conditions.展开更多
基金Project(51674305)supported by the National Natural Science Foundation of ChinaKey Project(1602FKDC007)supported by Science and Technology Program of Gansu Province,China+1 种基金Projects(2016YT03N101,2017A090905024)supported by Science and Technology Program of Guangdong Province,ChinaProject(NSFJ2015-K06)supported by Jiangxi University of Science and Technology,China
文摘In order to realize resource utilization of industrial tungsten residue and treatment of heavy metal wastewater in mining and metallurgical area of south China,a novel ceramsite was prepared with the main raw materials of diatomite and tungsten residue.The adsorption behavior of copper ions in solution on the ceramsite was investigated.Results indicated that the surface of the newly-developed ceramsite was rough and porous.There were lots of pores across the ceramsite from inner to outside.MnFe2O4 was one of the main components of the ceramsite.The Cu^2＋adsorption capacity by the ceramsite reached 9.421 mg/g with copper removal efficiency of 94.21%at 303 K,initial Cu^2＋concentration of 100 mg/L and dosage of 0.5 g after 300 min adsorption.With increase of ceramsite dosage,the total adsorption amount of Cu^2＋increased,but the adsorption capacity decreased.The adsorption capacity increased with the increase of solution p H.The isothermal adsorption of Cu^2＋by the ceramsite fitted the Freundlich model better.The adsorption mainly occurred on a heterogeneous surface,and was a favorable process.The adsorption process closely followed the pseudo-second kinetic equation.In initial stage of wastewater treatment,the adsorption process should be controlled mainly by diffusion,and the removal of Cu^2＋can be improved by enhancing agitation.
基金Key Research and Development Project of Shandong Province(2016ZDJS05B03)Key Research and Development Project of Shandong Province(2017CXGC0812)。
文摘Keyhole gas tungsten arc welding(K-TIG)of Q345 low alloy steel plates was simulated by using SYSWELD software.The temperature field of the K-TIG welding process was simulated with three different combined heat sources and was compared with the weld profile that was obtained experimentally.The temperature field that was obtained by a combination of a double ellipsoid heat source on the upper half and a three-dimensional Gauss heat source on the lower half was similar to the real situation.The effects of plate thickness,gap and welding speed on the deformation and stress of the K-TIG welded joints were investigated by K-TIG welding numerical simulation.A reduction in the thickness of the weld plates reduced the z-direction deformation and transverse residual stress;an appropriate gap reduced the residual stress and an increase in the welding speed reduced deformation after welding,but did not help to control the residual stress after welding.
基金financially supported by Shandong Provincial Key Research and Development Program, China (No. 2017GGX20140)Shandong Provincial Natural Science Foundation, China (Nos. ZR2014JL031 and ZR2018MEE016)
文摘The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element(FE) method. After the continuous rolling, the grains of the tungsten rod were refined, and the microhardness was improved; however, a ring region of abnormal grain growth was present at a distance of about 3/5 R(R is the radius of the rod) from the center of the cross section. FE modeling results showed that the equivalent residual strains were minimum around the region of abnormal grain growth; this was due to the release of strain energy by severe plastic deformation, leading a situation where the migration force of grain boundaries was higher than the pinning force of potassium bubbles. By decreasing the initial rolling temperature and rolling speeds, the inhomogeneity of the equivalent residual stain decreased, improving the microstructure uniformity of the doped tungsten.
文摘The first step in the production of tungsten is to enrich tungsten from two minerals wolframite((Fe,Mn)WO_(4))and scheelite(CaWO_(4))through the leaching process.The leaching residue usually contains a certain amount(2-5 wt%)of WO_(3) which is higher than that in the tungsten ore(generally less than 1 wt%).In addition,the leaching residue may also consist of other valuable elements such as Cu,Ta,Nb,Sn,Sc,Mn and Fe.Understanding the phases and their compositions present in the residue is one of the key steps for the efficient utilization.The typical residue sample is carefully analysed by electron probe X-ray microanalysis and X-ray fluorescence.A high-temperature process,which includes pre-reduction at 1000-1100℃and smelting reduction at 1450-1500℃,is proposed to efficiently recover the valuable elements.Experimental work and thermo-dynamic calculations confirmed that most of the valuable elements can be economically recovered with optimum conditions.
