The study on the effect of flotation purification on the performance of α-hemihydrate gypsum prepared from phosphogypsum

Phosphogypsum (PG) is a massive industrial solid waste. In this paper, PG was purified by flotation method, and α-hemihydrate gypsum (α-HH) was prepared by the autoclaving method. The morphology of α-HH was adjusted by adding different doses of Maleic acid and Aluminium sulfate. The results showed that after flotation purification, the impurity content in PG was significantly reduced, the soluble phosphorus content decreased from 0.48 to 0.07%, the PG purity increased from 73.12 to 94.37%, and the PG whiteness risen from 19.4 to 40.5. Then the performance of α-HH prepared from PG before and after purification was compared. Fixing the amount of aluminium sulfate at 0.2 wt%, the reaction temperature at 140 °C, and the reaction time at 120 min, the average length/diameter ratio of α-HH crystals decreased from 7.2 to 0.6 as the amount of Maleic acid increased from 0 to 0.17 wt%. When the amount of Maleic acid was 0.13 wt%, the α-hemihydrate gypsum reached the best mechanical properties. The mechanical strength of high strength gypsum prepared from PG concentrate was significantly better than that of raw PG, indicating that flotation purification can effectively improve the performance of PG. In this study, a new method of PG purification and resource utilization was proposed.

The Detection of Impurity Content in Machine-Picked Seed Cotton Based on Image Processing and Improved YOLO V4

The detection of cotton impurity rates can reflect the cleaning effect of cotton impurity removal equipment, which plays a vital role in improving cotton quality and economic benefits. Therefore, several studies are being carried out to improve detection accuracy. Image processing technology is increasingly used in cotton impurity detection, in which deep learning technology based on convolution neural networks has shown excellent results in image classification, segmentation, target detection, etc. However, most of these applications focus on detecting foreign fibers in lint, which is of little significance to the parameter adjustment of cotton impurity removal equipment. For this reason, our goal was to develop an impurity detection system for seed cotton. In image segmentation, we propose a multi-channel fusion segmentation algorithm to segment the machine-picked seed cotton image. We collected 1017 images of machine-picked seed cotton as a dataset to train the detection model and tested and recognized 100 groups of samples, with an average recognition rate of 94.1%. Finally, the image segmented by the multi-channel fusion algorithm is input into the improved YOLOv4 network model for classification and recognition, and the established V–W model calculates the content of all kinds of impurities. The experimental results show that the impurity content in machine-picked cotton can be obtained effectively, and the detection accuracy of the impurity rate can increase by 5.6%.

Development of a combined solution of pyrimidine nucleotides with vitamin B6

Pyrimidine nucleotides, namely uridine monophosphate and cytidine monophosphate, play an important role in the cellular metabolism of nerve fibers. The combination of these nucleotides with pyridoxine hydrochloride (vitamin В6) in one dosage form will allow us to fully implement the strategy of the complex neurotropic pharmacotherapy in neuropathies of various origins. To develop a stable solution, an important step at the stage of the composition development is to study the compatibility of active substances (active pharmaceutical ingredients - APIs) in solution. Samples of binary solutions and solutions containing all active substances were prepared and examined. The API interaction was determined by various parameters – changes in color, transparency, рН, the total impurity content, etc. Based on a comprehensive study of the processes of the API dissolution the optimal pH limits of the solution required for the stable existence of a combination of substances with different pH values of the medium have been substantiated and experimentally confirmed. As a result of the research, the optimal pH value of the solution recommended is 4.0-4.8. In the composition of substances the amount of water can be in an adsorbed or crystallized, or combined form. This fact should be taken into account in order to correctly calculate the actual amounts of initial ingredients when preparing the solution. The nature of the water component of APIs was clarified when studying the phase composition of samples on a powder diffractometer. The studies conducted have allowed us to determine the directions of further research for developing the composition of an injection drug. This research is in choosing the optimal buffer system and excipients-antioxidants.

THERMAL-INDUCED DOMAIN PROCESSES IN TRIGLYCINE SULFATE CRYSTALS WITH CHROMIUM IMPURITIES

В работе представлены результаты исследований термоиндуцированных доменных процессов в хромсодержащих кристаллах триглицинсульфата. Показано, что изменение температуры кристаллов ТГС: Cr в отсутствие внешних электрических полей сопровождается перестройкой доменной структуры, которая наиболее интенсивно происходит в области фазового перехода. Деполяризующее поле величиной ~1,4·10 В·м, которое порождается градиентным изменением температуры образца, вызывает процесс переключения его доменной структуры. В неотожженных кристаллах при концентрациях примеси, превышающих 5·10 вес. % процессы переключения затруднены, а интенсивность термоиндуцированных доменных процессов существенно ниже аналогичных для образцов с меньшим содержанием примеси. На интенсивность процессов переключения кристаллов ТГС: Cr существенное влияние оказывает скорость их нагревания. Зависимости интегрального числа скачков переполяризации от скорости нагревания образцов N = f (V) носят экстремальный характер. Экстремумы кривых N = f (V) лежат в интервалах скоростей (0,2-0,8) K·c. Доменная структура кристаллов ТГС:Cr состоит из матрицы основного домена, линзовидных и ламелеобразных доменов. Под воздействием электронного пучка наблюдается эволюция доменной структуры, сопровождающаяся ростом доменов, их слиянием и переключением образца. Высокотемпературный отжиг кристаллов приводит к их полидоменизации. The article presents the results of studies of thermally induced domain processes in chromium-containing crystals of triglycine sulfate (TGS). It is shown that a change in the temperature of TGS: Cr crystals in the absence of external electric fields is accompanied by a rearrangement of the domain structure, that occurs most intensively in the region of the phase transition. A depolarizing field of ~1,4·10 V·m, which is generated by a gradient change in the temperature of the sample, causes the process of switching its domain structure. In unannealed crystals at impurity concentrations exceeding 5·10 wt.%, switching processes are hindered, and the intensity of thermally induced domain processes is significantly lower than that for samples with a lower impurity content. The intensity of the switching processes of TGS: Cr crystals is significantly influenced by the rate of their heating. The dependences of the integral number of polarization-reversal jumps on the heating rate of the samples N = f (V) are extreme. The extrema of the N = f (V) curves lie in the rate intervals (0,2 - 0,8) K·c. The domain structure of TGS: Cr crystals consists of a matrix of the main domain, lenticular and lamellar domains. Evolution of the domain structure is observed under the influence of an electron beam, accompanied by the growth of domains, their coalescence, and sample switching. High-temperature annealing of crystals leads to their polydomenization.

Influence of the hydrodynamic degumming process on the quality of decorticated flax fibers

The study explored the impact of the hydrodynamic degumming process applied for decorticated monomorphic flax on fiber quality. The experiment was designed as the first stage of research leading to the development of a method for decorticated flax fiber elementarization and cottonization; in particular, effectively dividing the fiber bundles to ensure low linear density and reducing impurities in the content, to make the fibers suitable for cotton spinning systems. The degumming process of the decorticated fibers covered hydrodynamic disposal of the gluing substances, mainly pectins from the fibers, with use of a specially designed lab-scale Model Device for Physical Degumming of the Flax Fibers. The degummed fibers were tested for linear density, length, impurity content and chemical composition by thermogravimetric analysis combined with the analysis of evolved gases (Fourier transform infrared spectroscopy) and analysis of images of fiber cross-sections and longitudinal views from a scanning electron microscope. The study outcomes allowed us to determine the optimal parameters of the degumming process applied for decorticated flax fibers, in which the obtained fibers were of the highest quality. It was found that the optimal parameters of the process were a bath temperature of 30°C and a degumming process duration of 24 hours. These lab-scale process conditions were used in further work on the degumming process of flax fiber carried out on a semi-technical scale, followed by a mechanical cottonization of the fiber, at the final stage of the technological chain.

Effect of Impurities Control on the Crystallization and Densification of Polymer-Derived SiC Fibers

The polymer-derived SiC fibers are mainly used as reinforcing materials for ceramic matrix composites (CMCs) because of their excellent mechanical properties at high temperature. However, decomposition reactions such as release of SiO and CO gases and the formation of pores proceed above 1400 °C because of impurities introduced during the curing process. In this study, polycrystalline SiC fibers were fabricated by applying iodine-curing method and using controlled pyrolysis conditions to investigate crystallization and densification behavior. Oxygen and iodine impurities in amorphous SiC fibers were reduced without pores by diffusion and release to the fiber surface depending on the pyrolysis time. In addition, the reduction of the impurity content had a positive effect on the densification and crystallization of polymer-derived SiC fibers without a sintering aid above the sintering temperature. Consequently, dense Si-Al-C-O polycrystalline fibers containing β-SiC crystal grains of 50~100 nm were easily fabricated through the blending method and controlled pyrolysis conditions.

Experimental testing of the effectiveness of novel hydrocyclones for separation of impurities in biofuels

This paper investigates the potential sources of renewable energy, in particular biofuels. Biofuels tend to contain multiple harmful impurities that need to be separated if the biofuel is to have good energy performance, and the systems that run on it to produce electricity or heat are to operate more reliably. The paper discusses use of hydrocyclones as the most productive and reliable biofuel purification method. It dwells upon the factors that negatively affect separation of mixtures in a hydrocyclone, which are attributable to the complex hydrodynamics of the flow in such a unit. In order to eliminate these factors, the authors hereof have developed two hydrocyclone designs. An experimental test bench was designed and made to test these designs. Parts of the units were 3D printed from an environmentally friendly material. For testing, we used a biodiesel made from waste cooking oil with an impurity content of 23%. Experiments showed a maximum separation rate of 94.2%. The proposed solutions did improve the effectiveness of biodiesel mixture separation. These designs can be effectively used to separate non-homogeneous mixtures.

Decomposition test study on short-process mechanical strengthening equipment of alkali decomposition of tungsten ore

The traditional alkali decomposition process and equipment of tungsten ore are limited by the situation that the grade of tungsten ore resources is decreasingy and the impurity content is getting higher and higher. A set of high-efficiency alkali decomposition process equipment of tungsten ore based on mechanical strengthening is researched and developed in this paper. Fourteen groups of mechanical strengthening decomposition tests were carried out on three particle sizes of ore samples. which verifies the feasibility and reliability of strengthening the alkali decomposition of tungsten ore by the test prototype.

Structural Defects of Graphene Oxidation Reduction and Its High-Efficiency Structural Reforming Technology

The Hummers’ method is used to prepare graphene oxide and graphene powder, and the obtained powder material contains a large amount of oxygen-containing groups. Due to the effect of strong oxidants, there are many defects on the graphene body. Although a large number of oxygen-containing groups are reduced by the reduction reaction, the defects of the graphene body are numerous, which has a great influence on the conductivity of graphene and also limits the high carrier transport capability and application of graphene itself. Using industrial means, the graphene powder is highly reduced, and the ultrathin graphene powder is obtained, the graphene powder has extremely low impurity content, and the defects are substantially completely reduced. Then, these lay the foundation for its application in the battery industry.

Comparative Study of α-Hemihydrate Preparation from Phosphogypsum Before and After Flotation Purification

Phosphogypsum (PG) is a massive industrial solid waste. In this paper, PG was purified by flotation method, and α-hemihydrate gypsum (α-HH) was prepared by the autoclaving method. The morphology of α-HH was adjusted by adding different doses of Maleic acid and Aluminium sulfate. The results showed that after flotation purification, the impurity content in PG was significantly reduced, the soluble phosphorus content decreased from 0.48% to 0.07%, the PG purity increased from 73.12% to 94.37%, and the PG whiteness risen from 19.4 to 40.5. Then the performance of α-HH prepared from PG before and after purification was compared. Fixing the amount of Aluminium sulfate at 0.2wt%, the reaction temperature at 140°C, and the reaction time at 120min, the average length/diameter ratio of α-HH crystals decreased from 7.2 to 0.6 as the amount of Maleic acid increased from 0 to 0.17wt%. When the amount of Maleic acid was 0.13wt%, the α-hemihydrate gypsum reached the best mechanical properties. The mechanical strength of high strength gypsum prepared from PG concentrate was significantly better than that of raw PG, indicating that flotation purification can effectively improve the performance of PG. In this study, a new method of PG purification and resource utilization was proposed.