Preg-Robbing in Refractory Gold Ores: A Critical Review of Mineralogical Controls, Pretreatment Strategies and Flowsheet Selection

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Preg-robbing remains a major constraint in the processing of refractory gold ores, particularly those containing carbonaceous matter, fine clays, and iron-bearing phases capable of adsorbing dissolved gold during leaching. This review critically evaluates advances reported between 2020 and 2025, focusing on the mineralogical controls of preg-robbing, its interaction with gold dissolution chemistry, and the effectiveness of current mitigation strategies. Gold adsorption is governed by carbon structure, surface functional groups, sulfide associations, and textural features that control accessibility, determining whether adsorption is reversible or irreversible and, consequently, whether conventional recovery routes remain viable. Pretreatment options, including roasting, pressure oxidation, bio-oxidation, chemical passivation, and selective removal of reactive phases, are assessed in terms of metallurgical performance, operational complexity, energy demand, and environmental impact. The review also examines alternative lixiviants such as thiosulfate, glycine, and ammonia-based systems, highlighting their potential to reduce sensitivity to carbonaceous matter while emphasizing their dependence on mineralogy and process control. Rather than proposing a universal solution, the analysis defines decision-oriented criteria for flowsheet selection based on mineralogical and operational constraints, identifying the conditions under which specific approaches are technically robust and economically justified. Key research gaps are highlighted, particularly in the quantitative characterization of adsorption capacity and kinetics, and in the integration of mineralogical data into predictive process design frameworks.

Relationship Between Knowledge Level About Scabies and Scabies Symptoms Among Students Living in a Sports School Dormitory in Kupang, Indonesia: A Cross-Sectional Study

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Background: Scabies is a neglected tropical disease with high transmission risk in crowded living environments such as dormitories. Knowledge is often assumed to play a protective role, but empirical findings remain inconsistent.

Objective: To examine the association between the level of knowledge about scabies and the presence of scabies symptoms among students living in a sports school dormitory in Kupang, Indonesia.

Methods: An analytical cross-sectional study was conducted in July 2025 among 59 students selected using simple random sampling. Knowledge level was assessed using a structured questionnaire, while scabies symptoms were identified through physical examination based on cardinal signs. Data were analyzed using the Chi-square test.

Results: Most respondents demonstrated a high level of knowledge about scabies (79.7%). Scabies symptoms were identified in 25.4% of participants. Statistical analysis showed no significant association between knowledge level and scabies symptoms (p = 0.148).

Conclusion: High knowledge levels were not significantly associated with the absence of scabies symptoms. Environmental factors and intensive physical contact related to athletic activities may play a more substantial role in scabies transmission in dormitory settings.