ANALYSIS OF THE STRUCTURAL AND COMPOSITIONAL PROPERTIES OF RICE HUSK

Аннотация

This article presents a scientific analysis of the influence of the physical and chemical properties of rice husk, derived from locally cultivated rice varieties, on the separation process. During the research, the density, size, moisture content, and silica composition of the husk from several rice varieties were determined, and their impact on separation technology was assessed. The results show that husks with higher density and greater silica content require high-velocity airflow or vibration-based separation methods. The article provides formulas, physical models, and technological parameters aimed at increasing separation efficiency based on the morphological characteristics of the husk. It is also substantiated that universal machines are not suitable for all varieties, and the development of combined and automated separation systems is essential. The research findings offer practical recommendations for optimizing rice cleaning technologies andimproving thedesign of relevant equipment. Keywords: rice varieties, husk properties, silica content, density, air separation, cereal crops, morphological analysis, differential velocity. Introduction. Rice cultivation and its primary processing hold significant importance in grain crop technologies. The outer shell of the grain—the husk—is the main fraction to be separated during rice cleaning, and its physical and chemical properties directly affect process efficiency. Rice varieties differ considerably in their biological traits and adaptation to agro-climatic conditions. Specifically, their husk varies in density, moisture content, silica percentage, shape, andsize,all of which are critical indetermining thetechnological mode ofthecleaning process. The husk composition and characteristics of rice varieties grown in local agro-climatic conditions reflect the specific traits of each variety. For example, some varieties have brittle and lightweight husks, making them well-suited for air-based separation, while others are covered with a hard and dense husk, requiring vibrational or mechanical cleaning methods. A high percentage of silica in the husk composition increases dust generation during processing, raising thedemands onaspiration systems. Improving cleaning equipment and processes requires a deep understanding of the physical and chemical properties of rice husk, a thorough assessment of current technological solutions, and the development of new technologies. This study is based on such an approach—identifying differences in husk properties among various rice varieties and evaluating their effect on cleaning technology to justify effective separation methods. http://www.internationaljournal.co.in/index.php/jasass 737 Volume 15Issue 06, June 2025 Impact factor: 2019: 4.679 2020: 5.015 2021: 5.436, 2022: 5.242, 2023: 6.995, 2024 7.75 Literature Review. Initial processing of rice, particularly husk separation, is a critical stage in agrotechnology. Various sources contain studies on the morphological and physicochemical structure of rice grains. However, in-depth research on the husk characteristics of rice varieties grown under local agro-climaticconditions remains limited. The outer shell of cereal crops is classified by density, surface temperature, and silica (SiO₂) content. The density of rice husk typically ranges from 90 to 150 kg/m³. This range enables fractional separation by differential velocity in air-separation systems, as described by the followingphysical formula: 1 2 = ∙ ∙ ∙ Where: – air resistance force (N), – drag coefficient (0.3–0.5), – air density (1.2 kg/m³), 2 A–cross-sectional areaof thehusk (m²), –air velocity (m/s). 2 Experiments show that rice husk separati on in airflow occurs within the range of 1.5–2.5 m/s. For denser varieties (e.g., “Guliston” and “Zarafshan”), this value must exceed 2.3 m/s. According to analyses of mechanical sorting equipment, vibrational surfaces improve separation efficiency by 15–20% when dealing with harder husks. The efficiency of vibrational separation iscalculated as follows: = ∙100% Where:: – cleaning efficiency (%), – m a s s of correctly separated husk (kg), – totalhusk mass (kg). Local studies indicate that when silica content exceeds 18%, dust concentration in the aspiration system surpasses acceptable limits. For instance, the husk of the Zarafshan variety contains 20.3% silica, and without dust filters, concentrations above 1.5 mg/m³ were recorded. Additionally, literature notes that husk size distribution is a key factor in ensuring technological compatibility. Thefollowing tablecompares huskparameters for different varieties: Variety Average Size (mm) Silica (%) Density (kg/m³) Moisture (%) Lazer 5.5 17.2 130 10.5 Oqsholi 6.0 14.6 95 12.0 Guliston 4.5 19.1 150 9.2 Zarafshon 4.0 20.3 145 8.0 Table1.Characteristics of rice huskbyvariety http://www.internationaljournal.co.in/index.php/jasass 738 Volume 15Issue 06, June 2025 Impact factor: 2019: 4.679 2020: 5.015 2021: 5.436, 2