ТЕРМОДИНАМИЧЕСКИЙ АНАЛИЗ РАЗЛОЖЕНИЯ ФЕРРИТА ЦИНКА В ПЫЛИ ЭЛЕКТРОДУГОВОЙ ПЛАВКИ СТАЛИ ИЗВЕСТЬЮ

The paper studies the scientific basis of the pyrometallurgical treatment process for electric steelmaking dust containing zinc ferrites. Thermodynamic analysis of zinc ferrite decomposition by lime was performed. According to the calculated data analysis, dust requires adding at least 46 % of CaO to decompose more than 90 % of ZnFe2O4, and at least 60 % of CaO to decompose more than 95 % of ZnFe2O4. The calculation results were verified by the laboratory furnace experiments. Experimental dust calcination in air with lime added up to 60 % of dust mass at a temperature of 1000 °C and a holding time of 4 h confirmed that zinc ferrite is decomposed by calcium oxide with the formation of zinc oxide and dicalcium ferrite. In addition, 50 kg of sublimates per 1 ton of dust were obtained containing 29 % of lead and 15 % of zinc. Dust calcination with the addition of lime can be used to transform zinc from ferrite to a soluble oxide form. Intermediate products resulting from calcination can be used for zinc and lead recovery. After zinc leaching it is possible to obtain the iron-containing product applicable in ferrous metallurgy. The approach has a variety of technological advantages in comparison with the known Waelz process. In particular, calcination with lime requires lower temperature (1000 °C) than the known technology (1250 °C), it eliminates the second stage of Waelz treatment necessary to purify zinc oxide fed for leaching from halides, significantly reduces coke consumption and simplifies gas cleaning from dust due to the 6–8 times lower quantity of sublimates.Изучены научные основы пирометаллургической технологии переработки пылей электросталеплавильного производства, содержащих ферриты цинка. Выполнен термодинамический анализ разложения феррита цинка известью. Анализ полученных расчетных данных показал, что для разложения более чем 90 % ZnFe2O4 необходимо добавить к пыли не менее 46 % CaO, а для разложения более чем 95 % ZnFe2O4 – не менее 60 % CaO. Результаты расчетов проверены экспериментально на лабораторной печи. Экспериментальная прокалка пыли на воздухе с добавлением извести в количестве 60 % от массы пыли при температуре 1000 °C с временем выдержки 4 ч подтвердила, что процесс разложения феррита цинка оксидом кальция с образованием оксида цинка и двухкальциевого феррита имеет место. При этом также были получены возгоны в количестве 50 кг на 1 т пыли, содержащие 29 % свинца и 15 % цинка. Процесс прокалки пыли с известью можно применять для перевода цинка из феррита в растворимую оксидную форму. В результате прокалки могут быть получены промежуточные продукты для извлечения цинка и свинца. После выщелачивания цинка возможно получение железосодержащего продукта, который может быть востребован в черной металлургии. Использованный подход имеет ряд технологических преимуществ по сравнению с известной технологией вельцевания цинксодержащих металлургических пылей. В частности, процесс протекает при более низкой температуре (1000 °C) по сравнению с известной технологией (1250 °C), исключается вторая стадия вельцевания, необходимая для очистки от галогенидов поступающего на выщелачивание оксида цинка, значительно сокращается расход кокса, а также упрощается очистка газов от пыли из-за уменьшения количества возгонов в 6–8 раз

CW, Q-switched and mode-locking oscillations at 2.1 μm in novel Tm ³⁺:Lu₂O₃ ceramics lasers

Solid-state lasers at 2.1 μm having many applications for medical surgery, atmospheric wind lidar, gas detection, material processing and pumping of mid-IR optical parametric oscillators are attracting great interest in the last years. Tm- and Ho-doped sesquioxides (Tm3+:Lu2O 3, Tm3+:Sc2O3, Ho: 3+:Lu2O3 and others) having an extraordinary long-wavelength 2-μm luminescence band and a high thermal conductivity open up new opportunities for highly efficient laser generation at around 2.1 μm [1]. Transparent laser ceramic materials are attracting great interest as a substitute for the single crystals. Recently, the high-quality sesquioxides ceramics doped by Nd3+ or Yb3+ ions have demonstrated good potential for the efficient laser oscillation. This presentation is an overview of our investigations of the 2.1- μm lasers based on the novel Tm 3+:Lu2O3 ceramics with diode or laser pumping at 796 or 810 nm [2-6].</p

A Common Polymorphism G-50T in Cytochrome P450 2J2 Gene Is Associated with Increased Risk of Essential Hypertension in a Russian Population

The present study was designed to test whether common polymorphism G-50T within the promoter of human CYP2J2 gene is associated with increased risk of essential hypertension in a Russian population. We studied 576 unrelated subjects, including 295 patients with hypertension and 281 healthy subjects. Genotyping for polymorphism G-50T of the CYP2J2 gene was performed by polymerase chain reaction and restriction fragment length polymorphism techniques. The frequency of a −50T variant allele of CYP2J2 gene was significantly higher in patients with hypertension versus healthy controls (OR 4.03 95%CI 1.80–9.04 p=0.0004). The association of a −50GT genotype with hypertension remained significant after adjustment for age, gender and family history of hypertension by multivariate logistic regression (OR 4.78 95%CI 1.87–12.27 p=0.001). It has been found that OR for −50GT genotype × gender interaction (OR 4.48 95%CI 1.93–10.39 p=0.00048) was slightly higher than OR for −50GT genotype (OR 4.43 95%CI 1.91–10.29 p=0.00052), suggesting a weak effect of gender on the risk of hypertension in the heterozygous carriers of −50GT genotype. A family history of hypertension has no effect on the association between a −50GT genotype and hypertension. In present study we demonstrate for the first time that a CYP2J2*7 allele of the CYP2J2 gene is clearly associated with an increased risk of essential hypertension. Furthermore, this study highlights the importance of P-450 epoxygenase pathway of arachidonic acid metabolism in the pathogenesis of hypertensive disease