The extraction of potassium from a tablet mixture of K-feldspar ore and CaSO4by roasting was studied with a focus on the effects of the decomposition behavior of CaSO4on the potassium extraction process.The roasted sl...The extraction of potassium from a tablet mixture of K-feldspar ore and CaSO4by roasting was studied with a focus on the effects of the decomposition behavior of CaSO4on the potassium extraction process.The roasted slags were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy,and thermogravimetric（TG）analysis.The XRD analysis revealed that hydrosoluble mischcrystal K2Ca2（SO4）3was obtained by ion exchange of Ca^2＋ in CaSO4 and K^＋ in KAlSi3O8.Meanwhile,the intermediate product,SiO2,separated from KAl Si3O8and reacted with CaSO4to decompose CaSO4.The SEM results showed that some blowholes emerged on the surface of the CaSO4particles when they reacted with SiO2at 1200℃,which indicates that SO2and O2gases were released from CaSO4.The TG curves displayed that pure CaSO4could not be decomposed below 1200℃,while the mixture of K-feldspar ore and CaSO4began to lose weight at 1000℃.The extraction rate of potassium and decomposition rate of CaSO4were 62%and 44%,respectively,at a mass ratio of CaSO4to K-feldspar ore of 3：1,temperature of 1200℃,tablet-forming pressure of6 MPa,and roasting time of 2 h.The decomposition of CaSO4reduced the potassium extraction rate;therefore,the required amount of CaSO4was more than the theoretical amount.However,excess CaSO4was also undesirable for the potassium extraction reaction because a massive amount of SO2and O2gas were derived from the decomposition of CaSO4,which provided poor contact between the reactants.The SO2released from CaSO4decomposition can be effectively recycled.展开更多
In this paper, under different illuminations and random noises, focusing on the local texture feature's defects of a face image that cannot be completely described because the threshold of local ternary pattern(LT...In this paper, under different illuminations and random noises, focusing on the local texture feature's defects of a face image that cannot be completely described because the threshold of local ternary pattern(LTP) cannot be calculated adaptively, a local three-value model of improved adaptive local ternary pattern(IALTP) is proposed. Firstly, the difference function between the center pixel and the neighborhood pixel weight is established to obtain the statistical characteristics of the central pixel and the neighborhood pixel. Secondly, the adaptively gradient descent iterative function is established to calculate the difference coefficient which is defined to be the threshold of the IALTP operator. Finally, the mean and standard deviation of the pixel weight of the local region are used as the coding mode of IALTP. In order to reflect the overall properties of the face and reduce the dimension of features, the two-directional two-dimensional PCA((2D)~2 PCA) is adopted. The IALTP is used to extract local texture features of eyes and mouth area. After combining the global features and local features, the fusion features(IALTP+) are obtained. The experimental results on the Extended Yale B and AR standard face databases indicate that under different illuminations and random noises, the algorithm proposed in this paper is more robust than others, and the feature's dimension is smaller. The shortest running time reaches 0.329 6 s, and the highest recognition rate reaches 97.39%.展开更多
基金Supported by the National Key Research and Development Program(2016YFB0600904)Sichuan Province Science and Technology Project(2017GZ0377)Sichuan University Postdoctoral Research and Development Fund(2017SCU12017)
文摘The extraction of potassium from a tablet mixture of K-feldspar ore and CaSO4by roasting was studied with a focus on the effects of the decomposition behavior of CaSO4on the potassium extraction process.The roasted slags were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy,and thermogravimetric（TG）analysis.The XRD analysis revealed that hydrosoluble mischcrystal K2Ca2（SO4）3was obtained by ion exchange of Ca^2＋ in CaSO4 and K^＋ in KAlSi3O8.Meanwhile,the intermediate product,SiO2,separated from KAl Si3O8and reacted with CaSO4to decompose CaSO4.The SEM results showed that some blowholes emerged on the surface of the CaSO4particles when they reacted with SiO2at 1200℃,which indicates that SO2and O2gases were released from CaSO4.The TG curves displayed that pure CaSO4could not be decomposed below 1200℃,while the mixture of K-feldspar ore and CaSO4began to lose weight at 1000℃.The extraction rate of potassium and decomposition rate of CaSO4were 62%and 44%,respectively,at a mass ratio of CaSO4to K-feldspar ore of 3：1,temperature of 1200℃,tablet-forming pressure of6 MPa,and roasting time of 2 h.The decomposition of CaSO4reduced the potassium extraction rate;therefore,the required amount of CaSO4was more than the theoretical amount.However,excess CaSO4was also undesirable for the potassium extraction reaction because a massive amount of SO2and O2gas were derived from the decomposition of CaSO4,which provided poor contact between the reactants.The SO2released from CaSO4decomposition can be effectively recycled.
基金supported by the National Natural Science Foundation of China(No.51604056)the Chongqing Science and Technology Commission(No.cstc2015jcyj BX0066)
文摘In this paper, under different illuminations and random noises, focusing on the local texture feature's defects of a face image that cannot be completely described because the threshold of local ternary pattern(LTP) cannot be calculated adaptively, a local three-value model of improved adaptive local ternary pattern(IALTP) is proposed. Firstly, the difference function between the center pixel and the neighborhood pixel weight is established to obtain the statistical characteristics of the central pixel and the neighborhood pixel. Secondly, the adaptively gradient descent iterative function is established to calculate the difference coefficient which is defined to be the threshold of the IALTP operator. Finally, the mean and standard deviation of the pixel weight of the local region are used as the coding mode of IALTP. In order to reflect the overall properties of the face and reduce the dimension of features, the two-directional two-dimensional PCA((2D)~2 PCA) is adopted. The IALTP is used to extract local texture features of eyes and mouth area. After combining the global features and local features, the fusion features(IALTP+) are obtained. The experimental results on the Extended Yale B and AR standard face databases indicate that under different illuminations and random noises, the algorithm proposed in this paper is more robust than others, and the feature's dimension is smaller. The shortest running time reaches 0.329 6 s, and the highest recognition rate reaches 97.39%.
