Application of evolutionary rietveld method based XRD phase analysis and a self-configuring genetic algorithm to the inspection of electrolyte composition in aluminum electrolysis baths

The technological inspection of the electrolyte composition in aluminum production is performed using calibration X-ray quantitative phase analysis (QPA). For this purpose, the use of QPA by the Rietveld method, which does not require the creation of multiphase reference samples and is able to take into account the actual structure of the phases in the samples, could be promising. However, its limitations are in its low automation and in the problem of setting the correct initial values of profile and structural parameters. A possible solution to this problem is the application of the genetic algorithm we proposed earlier for finding suitable initial parameter values individually for each sample. However, the genetic algorithm also needs tuning. A self-configuring genetic algorithm that does not require tuning and provides a fully automatic analysis of the electrolyte composition by the Rietveld method was proposed, and successful testing results were presented. © 2018 by the authors. Licensee MDPI, Basel, Switzerland

Influence of Modifying with Al2O3 Nanofibers on the Properties of Wall Building Ceramics Based on Quartzofeldspathic Technogenic Raw Materials

Изучено влияние модифицирования нановолокнами Al2O3 на свойства стеновой строительной керамики на основе кварц-полевошпатовых отходов обогащения медно-молибденовых руд. Установлено, что при добавлении 0,6 масс.% нановолокон Al2O3 прочность керамики, спеченной при 1000 °C, возрастает от 38,3 до 58,5 МПа, водопоглощение снижается от 12,8 до 10,6 %, наблюдается возрастание морозостойкости керамического материалаThe effect of modifying with Al2O3 nanofibers on the properties of wall building ceramics based on quartzofeldspathic wastes from the enrichment of copper-molybdenum ores were studied. It was found that with 0,6 wt.% of Al2O3 nanofibers addition the strength of ceramics sintered at 1000 °C increases from 38,3 to 58,5 MPa, water absorption decreases from 12,8 to 10,6 %, an increase of the frost resistance was observe

Application of Evolutionary Rietveld Method Based XRD Phase Analysis and a Self-Configuring Genetic Algorithm to the Inspection of Electrolyte Composition in Aluminum Electrolysis Baths

The technological inspection of the electrolyte composition in aluminum production is performed using calibration X-ray quantitative phase analysis (QPA). For this purpose, the use of QPA by the Rietveld method, which does not require the creation of multiphase reference samples and is able to take into account the actual structure of the phases in the samples, could be promising. However, its limitations are in its low automation and in the problem of setting the correct initial values of profile and structural parameters. A possible solution to this problem is the application of the genetic algorithm we proposed earlier for finding suitable initial parameter values individually for each sample. However, the genetic algorithm also needs tuning. A self-configuring genetic algorithm that does not require tuning and provides a fully automatic analysis of the electrolyte composition by the Rietveld method was proposed, and successful testing results were presented

Copper Ferrite Nanoparticles Synthesized Using Anion-Exchange Resin : Influence of Synthesis Parameters on the Cubic Phase Stability

Copper ferrite is of great interest to researchers as a material with unique magnetic, optical, catalytic, and structural properties. In particular, the magnetic properties of this material are structurally sensitive and can be tuned by changing the distribution of Cu and Fe cations in octahedral and tetrahedral positions by controlling the synthesis parameters. In this study, we propose a new, simple, and convenient method for the synthesis of copper ferrite nanoparticles using a strongly basic anion-exchange resin in the OH form. The effect and possible mechanism of polysaccharide addition on the elemental composition, yield, and particle size of CuFe2O4 are investigated and discussed. It is shown that anion-exchange resin precipitation leads to a mixture of unstable cubic (c-CuFe2O4) phases at standard temperature and stable tetragonal (t-CuFe2O4) phases. The effect of reaction conditions on the stability of c-CuFe2O4 is studied by temperature-dependent XRD measurements and discussed in terms of cation distribution, cooperative Jahn–Teller distortion, and Cu2+ and oxygen vacancies in the copper ferrite lattice. The observed differences in the values of the saturation magnetization and coercivity of the prepared samples are explained in terms of variations in the particle size and structural properties of copper ferrite

Combined control of aluminum bath composition by X-ray diffraction and X-ray fluorescence analysis: Combined control of aluminum bath by XRD and XRF analysis

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The present paper provides a combined application of X‐ray diffraction (XRD) and X‐ray fluorescence (XRF) methods in process control for the analysis of aluminum baths of different compositions. Developed approaches to the combined calibration XRD and XRF methods, independent calibration XRF techniques and to the full‐profile automated Rietveld analysis of a bath composition are described. We established that combined XRD–XRF calibration techniques provide an accurate stable analysis of technological parameters in a wide range of traditional and low‐melting compositions due to an accurate quantification of CaF2, MgF2 and KF additives. The developed XRF techniques provide quantitative analysis of both cryolite ratio and aluminawith the accuracy of 0.03 and 0.25%wt. respectively, which is comparable with the technologically required accuracy. The evolutionary approach that automates full profile quantitative XRD analysis of bath composition and uses XRF data on Ca and Mg provides a better accuracy of measuring cryolite ratio compared to an accuracy of non‐automated analysis by Rietveld method. Combined application of the two X‐ray methods eliminates gross analytical errors and stabilizes overall performance of a smelter’s process control system

Стабильность сульфидных сорбентов на основе оксида кремния в водных средах. Часть 2. Носитель MCM-41

Sulfide sorbents based on MCM-41 have been synthesized. The chemical and thermal stability of the sorbents obtained has been investigated by physicochemical methods. It has been found that the acid treatment of the samples at the boiling point results in insignificant changes in structural, textural and sorption characteristics, demonstrating the total losses of the sorbent up to 15 wt%, which is considered to be connected with the dissolution of the malformed and unstructured particles of a silica matrix. The neutral and alkaline treatment induces more significant changes associated with the starting matrix dissolution (the weight loss is about 25-30 wt%). Nevertheless, the grafted organic functional layer is retained. The sorbents obtained are quite stable in the studied aggressive conditions and able to work over a long period of time in a variety of technological solutions and are not inferior to the well-known commercial sorbents with functional groupsСинтезированы сульфидные сорбенты на основе МСМ-41, исследована их химическая и термическая стабильность различными физико-химическими методами. Обнаружено, что кислотная обработка образцов при температуре кипения приводит к незначительным изменениям структурных, текстурных и сорбционных характеристик, демонстрируя общие потери сорбента до 15 масс.%. Указанный факт связан с растворением плохо сформированных и неструктурированных частиц кремниевой матрицы. Нейтральная и щелочная обработка приводит к более значительным изменениям, связанным с растворением исходной матрицы (потеря массы составляет около 25-30 масс.%). Тем не менее привитый органический функциональный слой сохраняется. Полученные сорбенты на основе МСМ-41, как и на основе SBA-15, относительно стабильны в изученных агрессивных условиях и способны работать в течение длительного периода времени в различных технологических раствора

Стабильность сульфидных сорбентов на основе оксида кремния в водных средах. Часть 2. Носитель MCM-41

Sulfide sorbents based on MCM-41 have been synthesized. The chemical and thermal stability of the sorbents obtained has been investigated by physicochemical methods. It has been found that the acid treatment of the samples at the boiling point results in insignificant changes in structural, textural and sorption characteristics, demonstrating the total losses of the sorbent up to 15 wt%, which is considered to be connected with the dissolution of the malformed and unstructured particles of a silica matrix. The neutral and alkaline treatment induces more significant changes associated with the starting matrix dissolution (the weight loss is about 25-30 wt%). Nevertheless, the grafted organic functional layer is retained. The sorbents obtained are quite stable in the studied aggressive conditions and able to work over a long period of time in a variety of technological solutions and are not inferior to the well-known commercial sorbents with functional groupsСинтезированы сульфидные сорбенты на основе МСМ-41, исследована их химическая и термическая стабильность различными физико-химическими методами. Обнаружено, что кислотная обработка образцов при температуре кипения приводит к незначительным изменениям структурных, текстурных и сорбционных характеристик, демонстрируя общие потери сорбента до 15 масс.%. Указанный факт связан с растворением плохо сформированных и неструктурированных частиц кремниевой матрицы. Нейтральная и щелочная обработка приводит к более значительным изменениям, связанным с растворением исходной матрицы (потеря массы составляет около 25-30 масс.%). Тем не менее привитый органический функциональный слой сохраняется. Полученные сорбенты на основе МСМ-41, как и на основе SBA-15, относительно стабильны в изученных агрессивных условиях и способны работать в течение длительного периода времени в различных технологических раствора

Твердые растворы в алюминиевых электролитах с участием LiF

The paper presents the investigation of the solid solutions formation in the fluoride system Na5Al3F14-Na3AlF6-K3AlF6 with the addition of LiF. Two local regions were under consideration. The first case concerns the possibility of potassium and sodium cations replacing with lithium in the elpasolite (K2NaAlF6) when LiF is added to the electrolyte. In the second, the effect of lithium fluoride on the chiolite (Na5Al3F14) was studied. The investigation was motivated by the need to control the composition of the electrolyte during the electrolytic production of aluminum. The electrolyte samples were obtained from the initial fluorides under laboratory conditions. Determination of crystal-chemical details of the structure of solid solutions was carried out by the method of full-profile analysis (Rietveld method) on multiphase polycrystalline samples. It was found that the addition of LiF in the structure of elpasolite is accompanied by a gradual substitution of lithium for sodium with the formation, ultimately, of the K2LiAlF6 phase with the lattice parameter a = 8.0779 Å. Potassium is not subject to substitution. No dissolution of LiF in the structure of cryolite (Na3AlF6) was found. It was shown that chiolite does not form solid solutions with LiF upon crystallizationПредставлены исследования образования твердых растворов в двух локальных областях системы Na5Al3F14-Na3AlF6-K3AlF6 с добавлением LiF. В первом случае рассмотрена возможность замещения катионов калия и натрия в эльпасолите (K2NaAlF6) на литий при добавлении в электролит LiF. Во втором изучено влияние фторида лития на хиолит (Na5Al3F14). Изучение фторидной системы обосновано необходимостью контроля состава электролита при электролизе алюминия. Исследования были выполнены на образцах, полученных из исходных фторидов в лабораторных условиях. Определение кристаллохимических деталей строения твердых растворов проведено методом полнопрофильного анализа (метод Ритвельда) на многофазных поликристаллических образцах. Установлено, что при добавлении LiF в структуре эльпасолита происходит постепенное замещение натрия на литий с образованием в конечном счете фазы K2LiAlF6 с параметром решетки а=8,0779 Å. Калий не подвергается замещению. Растворения LiF в структуре криолита (Na3AlF6) не обнаружено. Показано, что хиолит при кристаллизации не образует твердых растворов с Li