ANALYSIS IN MODERN PHYSICAL CHEMICAL METHODS

ABSTRACT

The chemical composition of some local raw materials from the south of the Republic of Uzbekistan and the Khondizha lead concentrate has been fully studied and analyzed using scanning electron microscopy, X-ray and differential thermal analysis. It has been established that unenriched local raw materials and lead concentrate can be added as components to glass by cleaning and enrichment with various additives. Quartz sands from the Sherabad, Zharkurgan, and Ugun deposits and lead concentrate from Khandiza were used as objects for glass synthesis, and their main functional and physicochemical properties were comprehensively studied. According to the chemical composition of the quartz sands used, compared to the quartz sands of Sherabad and Zharkurgan, the quartz sand of Ugun has a greater amount of silica, for this reason, experimental research work on glass synthesis samples was carried out mainly using Ugun quartz sand.

АННОТАЦИЯ

Химический состав некоторых местных сырьевых материалов юга Республики Узбекистан и Хондизинского свинцового концентрата полностью изучен и проанализирован с использованием методов сканирующей электронной микроскопии, рентгеновского и дифференциально-термического анализа. Установлено, что необогащенное местное сырье и свинцовый концентрат могут быть добавлены в качестве компонентов, стекла путем очистки и обогащения различными добавками. В качестве объектов для синтеза стекла использованы кварцевые пески месторождений Шерабад, Жаркурган, Угун и свинцовый концентрат Хандизы, всесторонне изучены их основные функциональные и физико-химические свойства. По химическому составу использованных кварцевых песков, по сравнению с кварцевыми песками Шерабад и Жаркурган, кварцевый песок Угуна имеет большее количество кремнезема, по этой причине экспериментально исследовательские работы образцов синтеза стекла проводились преимущественно с использованием Угунского кварцевого песка.

Keywords: local raw materials, lead concentrate, chemical composition, physical chemical analysis, scanning electron microscope, X-ray, differential thermal analysis.

Ключевые слова: местное сырье, свинцовый концентрат, химический состав, физико-химический анализ, сканирующий электронный микроскоп, рентгенография, дифференциально-термический анализ.

Introduction. In order to meet the needs of the world's manufacturing and service industries, scientific research is being conducted to synthesize colorless, colored, transparent and functional glass materials with unique properties based on various natural and artificial raw material components, develop their composition and production technologies. In this regard, when synthesizing glass materials of the required level, special attention is paid to determining the chemical and mineralogical compositions of raw material components, controlling the physicochemical processes occurring at high temperatures during their thermal treatment, phase transitions, silica polymorphism, the main factors affecting the formation of new crystal phases and liquefaction, as well as determining the physicochemical, functional and aesthetic properties of the obtained glass material samples.

One of the current problems facing scientists in the field of construction and engineering today is the creation of effective compositions and innovative technologies for obtaining transparent glass and special materials based on them, based on local raw materials. In this regard, it is important to conduct a comprehensive physicochemical study of local raw materials and determine the prospects for their use.

The total explored reserves of the Khandiza deposit are about 1.5 million tons of lead, 700 thousand tons of lead, 180 thousand tons of copper and 2.3 thousand tons of silver.

In the optical method of physicochemical analysis, concepts such as microscopes - polarizing microscopes and metallographic microscopes, micrographs and micrographs, crystal forms and syngonies are often encountered. The microscopy method is a method aimed at using a microscope in scientific research and using microscopic preparations to determine the specific properties of very small, highly dispersed particles that are visible only with a microscope. It allows the analysis of very small amounts of substances using precise chemical methods [1].

The following local raw materials and lead concentrate were used as objects for glass synthesis: quartz sands from the Sherabad, Zharkurgan and Ugun deposits and lead concentrate from Khandiza.

The purpose of the research is to fully study and analyze the composition and structure of local raw materials and lead concentrate using chemical, scanning electron microscopic, X-ray and differential thermal analysis methods.

The objectives of the research:

to determine the possibility of adding unenriched local raw materials and lead concentrate as glass components after purification and enrichment from various additives;

to conduct a comprehensive study of their main functional and physicochemical properties;

to synthesize glasses from natural raw material components based on Sherabad, Jarkurgan, Ugun quartz sand deposits and Khandiza lead concentrate;

to determine the effect of temperature on the glass synthesis process using natural raw material components.

Table 1.

Below shows the chemical compositions of the local raw materials and lead concentrate used for glass synthesis

Scanning electron microscope (SEM) is a type of electron microscopy designed to directly study the surface of solids and uses a relatively low-energy focused electron beam as an electron probe that is continuously scanned over the sample.

Morphological studies of the surface of the samples were carried out using a SEM - EVO MA 10 (Zeiss, Germany) scanning electron microscope. The experiments were carried out in a scanning electron microscope as follows: to carry out the sample preparation process, a round holder made of a metal alloy was used, on which aluminum foil with a double-sided adhesive surface was glued, and the required amount of test samples was applied to it.

Table 2.

Below shows the amount of chemical elements in the composition of the Khondiza lead concentrate

Figure 1. Scanning electron microscopic image of the structure of lead concentrate in Khandiza

As can be seen from the table above, according to the results of the analysis of lead concentrate using a scanning electron microscope, it was determined that the following elements were present in its composition: Pb-28.6%; Fe-17.6%; Zn-14.7% and S-12.4%, which are the main rock-forming elements of the compound, and the remaining elements in small quantities are additives.

Figure 2. Differential thermal analysis (DTT) of lead concentrate in Khandiza

Thermography is the study of the processes that occur during the heating of inorganic substances and silicate materials. They are usually associated with heat release and heat absorption [2]. There are many types of thermography, one of the most important of which is differential thermal analysis (DTA) [3-7].

Figure 2 below shows the DTA of the Khandiza lead concentrate.

The results of the differential thermal analysis of the sample of Khandiza lead concentrate are presented in Fig. 2, based on which the occurrence of 3 endo-effects and 2 exo-effects was observed in the thermal curve.

In the thermal curve, the endoeffect formed at the temperature of 393.8℃ is related to the release of hydrate waters, the one at the temperature of 541.8℃ is the release of chemically bound water, and at 587.3℃ it is the modification change of quartz. From the exothermic effect that occurred, 787.2℃ is due to the phase transition temperature of two lead silicates to lead silicate, and the other one is due to the liquid state of lead silicate at 827.6℃. Thus, using chemical reagents, as well as natural quartz sand and lead concentrate, samples of transparent-colorless glass materials were synthesized and their main functional and physicochemical properties were comprehensively studied. DTA and TG measurements of the Khonjiza lead concentrate were performed on a STA PT 1600 synchronous thermal analyzer manufactured by the German company Linseis, measurements were carried out in an oxidizing environment at a speed of 20 S/min.

Figure 3 below shows the DTA of Sherabad quartz sand.

Figure 3. Differential thermal analysis (DTT) of Sherabad quartz sand

Figure 4. X-ray image of Sherabad quartz sand

The temperature of Sherabad quartz sand started at 25℃ and thermal processes remained constant up to 550℃, with a high exoeffect observed between 550℃ and 735℃. This is due to the partial melting of the material. If we examine the mass, the mass decreased steadily from the initial temperature to 535℃. From 535℃ to 730℃, the mass decreased sharply by a small amount, and by the end of the process, the mass decreased by 2.5%.

Figure 4 below shows the X-ray diffraction pattern of Sherabad quartz sand.

When analyzing Sherabad quartz sand using the X-ray diffraction method, its composition was as follows: quartz - d = 0.420; 0.344; 0.222; 0.212; 0.197; 0.181; 0.166; 0.154; 0.138; 0.137 nm and anorthite - d = 0.322; 0.244; 0.226 nm. Sherabad quartz sand contains quartz and anorthite minerals.

The mineralogical composition of Ugun quartz sands was studied using the X-ray phase method (Fig. 5). The mineralogical composition of this natural sample of quartz sand (Fig. 5a) is represented mainly by β-quartz minerals (d = 0.344; 0.322; 0.222; 0.212; 0.197; 0.181; 0.166; 0.154; 0.138; 0.137 nm), a small amount of calcite (d = 0.226 nm), albite (d = 0.244 nm), it was also experimentally established that the diffraction lines of low intensity belong to clay and organic inclusions in quartz sand.

Figure 5. X-ray diffraction patterns of natural Ugun quartz sand samples (a), calcined at 900℃ (b) and 1450℃ (c)

The formation of a new crystalline phase was observed in the X-ray diffraction pattern of Ugun quartz sand samples fired at high temperatures (900℃ and 1450℃) (Fig. 5b, Fig. 5c). It was determined that the mineralogical composition of the sample fired at 900℃ consists of the minerals - α-quartz - d = 0.421; 0.332; 0.227 0.222; 0.212; 0.197; 0.181; 0.166; 0.154; 0.138 nm, a small amount of anorthite - d = 0.327 nm and albite - d = 0.256; 0.244 nm. As a result of X-ray phase analysis it was established that the diffraction maxima on the X-ray diffraction pattern of this sample of quartz sand fired at 1450℃ correspond to the crystalline phases of minerals - β-quartz - d = 0.421; 0.331; 0.247; 0.227; 0.212; 0.197; 0.181; 0.166; 0.154; 0.145; 0.138 nm, α-cristobalite - d = 0.401; 0.283; 0.312; 0.193; 0.187; 0.161 nm and albite - d = 0.244 nm.

Conclusion. In conclusion, the results of differential thermal analysis of local raw materials and lead concentrate are presented in Figures 2 and 3. According to the results of modern physicochemical analysis, it was determined that unenriched raw materials can be added as glass components as a result of purification and enrichment of various additives, and their specific properties were analyzed and fully studied using modern physicochemical methods. Quartz sands from the Sherabad, Jarkurgan, and Ugun deposits and lead concentrate from Khandiza were used as objects for glass synthesis.

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