The lichens in aluminum plants vicinities of Irkutsk region

The aim of our work was to assess the diversity of lichens in the forests polluted by the air emissions fromthe Bratsk (BRAZ), Irkutsk (IRKAZ) and Taishet (TAZ) aluminum smelters, as well as in the background (non-polluted)territories, similar to those by natural and forest-growing conditions. 102 wide-distributed lichen species were found onplots. This amount is due to the fact that the wood tier is sparse and forophytes composition is depleted. The lichen diversity varies in different types of vegetation and according to the influence of anthropogenic factors. Species diversity in vicinities of smelters and in buffer zones are similar, excluding control zones with dark-conifers forests. It’s established that as wemove closer to the aluminum plants – to the IRKAZ and especially BRAZ, the projective cover, the total number of speciesdecreases, and their species composition changes. Clear morphological changes of lichen thalloma were observed in theimpact zone of the BRAZ. Relatively resistant to atmospheric pollution lichens are found in the impact and buffer zonesin vicinities of plants. Lichens are absent in the crowns and trunks, but their abundance increases on bases of trees trunks.

Comprehensive Assessment of Working Conditions and Occupational Disease Rates at Mining and Metallurgical Enterprises

The paper presents the results of hygienic assessment of the working environment and work process factors at surface and underground ore mining operations, ferrous metallurgy plants and aluminum production facilities. It has been established that workers are affected by a complex of production factors (dust, toxic substances, noise, vibration, unfavorable micro climate, etc.), the level of which often exceeds the hygienic standards. The workplace conditions of the primary jobs at these enterprises in 60-80% of cases are classified as hazardous, i.e. Class 3 of various hazard degrees. The incidence of occupational diseases remains high, especially in underground mining and at aluminum production plants. The specific features of mining and metallurgical operations and the severity of unfavorable production factors determine the structure of occupational morbidity. Occupational respiratory diseases are most common among workers in the ferrous metallurgy industry and account for 70.3% in total. Vibration-induced pathologies are most frequently diagnosed among excavator, bulldozer and dump truck operators, and account for 52.9% of all the diagnosed occupational diseases. Hearing organ pathology in the form of neurosensory loss of hearing among workers of mining and metallurgical enterprises ranges from 10.2% (aluminum smelters) to 22.7% (ferrous metallurgy plants) in the occupational morbidity structure. Chronic intoxication with fluorine compounds at aluminum smelters was diagnosed in 68.1% of cases. The results obtained confirm the pressing need to improve the working conditions, introduce preventive measures based on the primary prevention principles, and reduce the risk factors of health problems among the workers.

Recycling of Spent Pot Lining First Cut from Aluminum Smelters by Utilizing the Two-Step Decomposition Characteristics of Dolomite

Spent Pot Lining First Cut (shortened to SPL-1cut) is a solid waste discharged from a primary aluminum electrolytic production process. SPL-1cut is classified as hazardous waste in China because it contains large amounts of soluble sodium fluoride and a tiny amount of cyanide. Most of SPL-1cut is carbon—about 65%—and its calorific value is 22.587 MJ∙kg−1. There is a high level of sodium fluoride in SPL-1cut—about 15%—and sodium fluoride is randomly distributed in the carbon granule. The recycling of SPL-1cut using dolomite as a reactant, based on the characteristics of the two-step decomposition of dolomite at a high temperature, is discussed. The recycling of SPL-1cut was performed under the following heating conditions: the heating temperature was 850 °C, the holding time was 120 min, and 40% of the dolomite was added to the SPL-1cut. It was found that the cyanides are completely oxidized and decomposed, and dolomite is decomposed into MgO and active CaCO3. At the same time, NaF reacts with active CaCO3 and converts into CaF2. The results provide references for using SPL-1cut as an alternative fuel in the dolomite calcination process of the Pidgeon Process.

Assessment of carcinogenic risks to workers of the main enterprises of the Irkutsk region

The purpose of research is the assessment of the individual cancer risk (ICR) for workers of the basic occupations in key branches of industry of the Irkutsk region. There was executed the calculation of ICR levels for workers of the basic occupations of the aircraft industry, aluminum smelters and vinyl chloride production plants. The estimation of the exposure for workers was carried out according to long-term time-weighted average concentrations in the air of the working area, for the population - on annual average concentrations in the ambient air. To assess the risk that is not associated with the profession, the dose was calculated for the period of life (70 years). When calculating the toxicant doses in the working area there were used the “standard” indices ofpulmonary ventilation for adults, body weight, the work experience in the contact with carcinogens of 30 years, the number of days in the contact of 240, the duration of the working time 8 or 12 hours (in accordance with the working hours) duration. ICR for the Irkutsk population amounted of 3.08E-04, in Shelekhov - 4.8E-05, Sayansk - 1.1E-05. The amount of risk depends on the content offormaldehyde in all territories and chromium VI in cities of Irkutsk and Shelekhov. ICR for workers of basic occupations of studied plants in dozens of times are higher than for the urban population. Priority carcinogens are: chromium VI, nickel, formaldehyde, silicon dioxide -for the aircraft plant employees; 1,2-dichloretan, vinyl chloride - for the workers of vinyl chloride production plant; benzopyrene - for the aluminum smelter workers.