Smelter Potrooms Research Articles

Life‐threatening heat‐related illness with severe hyponatremia in an aluminum smelter worker

Heat stress is a recognized occupational hazard in aluminum smelter pot rooms. This is the report of an unusual and complex case of heat‐related illness in an aluminum smelter worker. The 34‐year‐old male US worker developed life‐threatening heat‐related illness in August 2018, on his first day back at work after a 7‐day absence. The worker initially presented with bilateral hand then all‐extremity cramping followed some hours later by a generalized seizure and acute mental status changes, including combativeness. Emergency room evaluation identified a serum sodium level of 114 mmol/L. Acute liver and kidney injury ensued along with profound rhabdomyolysis, with peak total creatinine phosphokinase level reaching over 125 000 units/L at 3 days post incident. Initial ventilatory support, careful fluid resuscitation, and electrolyte management were provided. Metabolic encephalopathy resolved. Complications included sepsis. After 5 days in the intensive care unit and eight additional days of inpatient management, observation, and the initiation of rehabilitation, the worker was discharged. Residual effects include polyneuropathy of upper and lower extremities and the postdischarge magnetic resonance imaging finding of a cerebellar lesion. Prevailing considerations in the differential diagnosis included exertional heat stroke and/or exertion‐associated hyponatremia with encephalopathy.

Visualisation and identification of peak exposure events in aluminium smelter pot rooms using hydrogen fluoride and aerosol real-time portable spectrometers

A recently developed novel portable real-time hydrogen fluoride spectrometer was used with an aerosol PM10 spectrometer under a PIMEX telemetric measurement strategy to visualize and identify simultaneous occupational air peak exposure events to hydrogen fluoride and PM10 aerosol sub-fractions in aluminium smelter pot rooms using Søderberg or Prebake anode technologies. The hydrogen fluoride and the aerosol concentration data measured during different work operations are plotted and evaluated applying the synchronised videos and air concentrations measured by the spectrometers. The main point-emission sources of HF and PM10 were identified and assessed. The major finding in the study was that the main source of PM10 and HF was partly open cells in a Søderberg pot room, whereas in a Prebake pot room, the point emissions of the two contaminants were associated with hot bath residues and hot replaced anodes. In order to prevent the simultaneous exposure to HF and PM10 among pot room workers it is important to prevent workers from being close to these point-sources under unfavourable ventilation. Storage of hot residues outside electrolytic cells without any point source ventilation should not occur.

Occupational exposure to beryllium in primary aluminium production

Alumina used in the production of primary aluminium contains Be which partly vaporises from the cryolite bath into the workroom atmosphere. Since Be may be toxic at lower exposure levels than previously thought, the personal exposure to Be among workers in 7 Norwegian primary smelters has been assessed. In total, 480 personal Respicon® virtual impactor full shift air samples have been collected during 2 sampling campaigns and analysed for water soluble Be, Al and Na using inductively coupled plasma optical emission spectrometry. In addition, water soluble F(-) has been measured by ion chromatography. The Be air concentrations in the inhalable, thoracic and respirable aerosol fractions have been calculated. The Be concentrations in the inhalable aerosol fraction vary between the different smelters. The highest GM concentration of Be in the inhalable fraction (122 ng m(-3), n = 30) was measured in the prebake pot room of a smelter using predominantly Jamaican alumina where also the highest individual air concentration of 270 ng m(-3) of Be was identified. The relative distribution of Be in the different aerosol fractions was fairly constant with the mean Be amount for the two sampling campaigns between 44-49% in the thoracic fraction expressed as % of the inhalable amount. Linear regression analysis shows a high correlation between water soluble Be, Al, F and Na describing an average measured chemical bulk composition of the water soluble thoracic fraction as Na(5.7)Al(3.1)F(18). Be is likely to be present as traces in this particulate matter by replacing Al atoms in the condensed fluorides and/or as a major element in a nanoparticle sized fluoride. Thus, the major amount of Be present in the work room atmosphere of Al smelter pot rooms will predominantly be present in combination with substantial amounts of water soluble Al, F and Na.

Hygroscopic properties of the workroom aerosol in aluminium smelter potrooms: a case for transport of HF and SO2into the lower airways

The hygroscopic behaviour of individual aerosol particles from workplaces in a primary aluminium smelter was investigated by environmental scanning electron microscopy. At a high relative humidity, comparable with the human respiratory tract, most particles encountered in the Søderberg and Prebake potrooms either undergo partial deliquescence (leading to a water droplet with an insoluble core) or form thin water films at the surface. As gaseous HF and SO(2) are highly soluble in water, the aerosol particles may act as carrier for these two gases into the alveolar region of the lower respiratory tract. Based on a one-dimensional mass balance model, it is estimated that under peak exposure conditions (particle surface area concentration of 10(-4) cm(2) cm(-3)) approximately 10% of the initial gaseous HF may be transferred to the particle phase. For SO(2), this fraction is much lower (approximately 1%). These results indicate that at least HF may penetrate deeper into the lung in the presence of soluble particles or particles that form surface water films compared to HF alone.

Continuous Measurement of Peak Hydrogen Fluoride Exposures in Aluminum Smelter Potrooms: Instrument Development and In-Plant Evaluation

The aluminum smelting process continuously evolves both sulfur dioxide (SO 2 ) and hydrogen fluoride (HF) gases. The vast majority of these evolved gases are captured by local exhaust ventilation systems and transported to fume treatment centers. Any gas escaping the ventilation systems could create the potential for workplace exposures. Currently, there are no commercially available sensors that are capable of selectively measuring peak concentrations (< 10 sec) of HF in the presence of SO 2 . This measurement capability is critical for facilitating a better understanding of the etiology of respiratory health effects. This article presents the development and in-plant testing of a portable, tunable diode-based HF sensor that shows equivalent or improved performance relative to NIOSH Method 7902 and is capable of measuring short-term personal peak HF exposure potentials in operating aluminum smelters.

Factors Influencing the Relationship Between Benzo(a)pyrene and Other Particulate Polycyclic Aromatic Hydrocarbons at a Soderberg Aluminum Smelter

P-596 Introduction: Occupational and environmental exposure to polycyclic aromatic hydrocarbons (PAH) occurs as complex mixtures. Exposure to PAH mixtures, such as in primary aluminum smelting, increases cancer risks, but the role of individual PAHs is unknown. Benzo(a)pyrene (BaP) has routinely been used as a marker of PAH exposure, although a few other PAHs seem to be more potent carcinogens in animal studies. The PAH mixtures vary both between and within industries, which complicates the comparison of dose-response relationships across studies even when the same marker of exposure is used. Understanding the factors influencing the relationship between BaP and other PAHs within a mixture may allow for retroactively assessing exposures to these other components and will facilitate comparisons across studies and industries. We investigated the factors that influence the relationship between BaP and other PAHs within an aluminum smelter. Methods: We used 431 personal air measurements analyzed for BaP and 8 other particulate PAHs that were collected between 1978 and 2001 within the aluminum smelter potrooms. Using linear regression we examined differences in the log-transformed PAH/BaP ratio due to anode paste composition (4 types), potroom building, season, and job. The variable potroom building (3 locations) represented differences in technology, process conditions, and building properties between locations. The predicted PAH/BaP ratios were multiplied by BaP relative potency factors to provide an estimate of the relative toxicity of the mixture. Results: For three of the four anode paste types BaP was very strongly correlated with individual particulate PAHs (r> 0.93); however, 70% of the measurements were collected for one job, pot operator. In linear regression, between 23% and 89% of the variability in the log-transformed PAH/BaP ratio was explained by season, anode paste type, potroom building, and job, depending on the PAH. The relative toxicity of the mixture varied more across job (2.1–3.5) than across anode paste composition (1.8–2.8) or potroom building (2.3–2.5). BaP and benzo(ghi)pyrene accounted for 72–82% of the mixture's relative toxicity for the most common anode paste. Although dibenzo(a,h)anthracene is more potent, it accounted for only 1–2% of the mixture's carcinogenicity. Conclusions: Seasonal, job, and location differences in the relationship between BaP and other PAHs have not been previously reported. Assuming that the PAH mixture is constant for a given time period would not account for important job and location differences in the PAH mixture. As such, using a single PAH, such as BaP, would likely introduce exposure misclassification in epidemiologic studies.

A study of the feasibility of using mathematical optimisation to minimise the temperature in a smelter pot room

Health hazards arise in large industrial workshops (such as aluminium pot rooms) due to the production of heat by the process equipment inside these workshops, which leads to high temperatures around these pieces of equipment. The heat production is sometimes accompanied by the release of polluting gases and dust particles that are dispersed throughout the workshop. The only large-scale and cost-effective way to ventilate these workshops is through natural ventilation. The effectiveness of the ventilation depends on the architectural shape of the building, the heat source locations and the openings of the windows, louvers and/or roof ventilators through which the air is allowed to enter and exit. This paper describes the investigation into the feasibility of using mathematical optimisation to determine the ideal window slat angles for different prevailing wind conditions. The proposed optimisation methodology employs computational fluid dynamics software (FLUENT), coupled to a computationally economic optimisation algorithm (Dynamic-Q) to determine the optimum slat angles to minimise the maximum temperature. The results of this feasibility study on a large-scale aluminium smelter pot room in Inota, Hungary, show that this is a viable methodology to determine the optimum inlet configuration.

Optimal adjustment of the number of air changes of a smelter pot room by using mathematical optimisation

The only large-scale, cost-effective way to exhaust contaminated air from the furnace pot room of an industrial plant is through natural ventilation. The effectiveness of the ventilation depends, amongst others, on the openings of the windows through which the air is allowed to enter and exit the workshop. The ventilation is also directly influenced by the prevailing weather outside the building. An appropriate measure that characterises the ventilation within the workshop is the number of air changes per hour, and ideally, it should be close to a prescribed value for all weather conditions. This requirement can be met by the appropriate adjustment of the opening angles of the inlet and outlet window slats. This paper reports on the feasibility of using mathematical optimisation to determine the ideal window slat angles for different prevailing wind conditions. The proposed optimisation methodology employs computational fluid dynamics software (FLUENT), coupled to a computationally economic optimisation algorithm (Dynamic-Q), to determine the optimal slat angles. Results of the successful application of the proposed optimisation procedure to an example problem of a large-scale aluminium smelter pot room are presented.

Characterization of individual aerosol particles in workroom air of aluminium smelter potrooms

Aerosol particles with aerodynamic diameters between 0.18 and 10 microm were collected in the workroom air of two aluminium smelter potrooms with different production processes (Soderberg and Prebake processes). Size, morphology and chemical composition of more than 2000 individual particles were determined by high resolution scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on chemical composition and morphology, particles were classified into different groups. Particle groups with a relative abundance above 1%(by number) include aluminium oxides, cryolite, aluminium oxides-cryolite mixtures, soot, silicates and sea salt. In both production halls, mixtures of aluminium oxides and cryolite are the dominant particle group. Many particles have fluoride-containing surface coatings or show agglomerations of nanometer-sized fluoride-containing particles on their surface. The phase composition of approximately 100 particles was studied by transmission electron microscopy. According to selected area electron diffraction, sodium beta-alumina (NaAl(11)O(17)) is the dominant aluminium oxide and cryolite (Na(3)AlF(6)) the only sodium aluminium fluoride present. Implications of our findings for assessment of adverse health effects are discussed.

Theoretical aspects of fluoride air contaminant formation in aluminium smelter potrooms

The amount of particulate fluorides evolved from aluminium electrolysis cells is not entirely accounted for by the fluorides entrained in the anode gas. The largest additional source of particulate fluoride formation is by direct evaporation of fluorides into the anode gas stream and subsequent condensation on the drops of electrolyte generated in the process of bubble burst. A theoretical model was used for the calculation of the main physical parameters responsible for the formation of particle nuclei when the hot anode-gas is mixed with ambient air. The results of these calculations are in agreement with experimental observations reported in the literature. In particular, the size distribution, composition and morphology of the nano-particles support the theory of a vapour condensation mechanism under conditions of extreme supersaturation, but further studies are necessary.

Approaches to Handling Environmental Problems in Mining and Metallurgical Regions

1. Environmental problems related to mining in the industrial regions of Europe W. Leal Filho. 2. Environmental problems in the mining and metallurgical Donbass region S. Kurulenko. 3. The impact of metallurgical-mining enterprises on the transformation of the Biosphere and Noobiosphere I. Khodakovshy, et al. 4. Impact of the metallurgical industry on the coastal ecosystem of Black Sea countries I. Rudevna. 5. Sustainable water management, a matter of looking forward P.J.H.van den Berg. 6. Some facts on the links between human and environmental health in the Dniepro region A. Prykhodchenko, et al. 7. An overview of the environmental problems in the mining sector of the Ukraine G. Averin. 8. Methods for environmental audit in a mining complex S. Zenchanka, et al. 9. Life cycle assessment implementation and its financial aspects in the Polish mining industry M. Goralczyk. 10. The tailings dam failures in Maramures county, Romania and their transboundary impacts on river systems P.A. Brewer, et al. 11. Environmental protection in the steel industry, exemplified by ThyssenKrupp Stahl AG, Duisburg G. Still. 12. Development of approaches to sustainability for the metallurgical industry using mathematical modelling I. Butorina, P. Kharlashin. 13. Prospects of structural reconstruction of the mining and metallurgical complex on the basis of use of iron ores produced by hydraulic mining through boreholes N. Lukianchikov, L. Gagut. 14. Ecological problems of the geological environment caused by activities of the metallurgical plant KCM(Bulgaria) A. Benderov, et al. 15. OMENTIN an information network about mining and environmental technologies J. Foldessy, B. Bodo. 16. Tools and methods for using clean technologies in the mining and metallurgical regions of NIS countries W. Zadorsky. 17. Results of the EcoLinks project devoted to cleaner metallurgical production in the Donbas region: options for cleaner recycling of nickel bearing wastes at the Konstantinovka plant VtorMet V.M. Sokolov, et al. 18. Formation and valorisation of blast furnace mud from usage and treatment of the industrial water in the iron and steel corporation Sartid A.D. Smederevo L. Sekulik, P. Lalic. 19. The usage of pneumatic conveying systems in handling environmental problems in the metallurgical and mining industry J. Lahr, W. Kaulbars. 20. Use of the melting-gasification process for processing metallurgical sludges R. Lahr, et al. 21. Intensification of ventilation and minimisation of emissions in aluminium smelter potrooms S. Szabo. 22. Environmental effects of ferrous slags comparative analyses and a systems approach in slag impact assessment for terrestrial and aquatic ecosystems L. Svirenko, et al. 23. Perspectives in utilizing ash and slug wastes from the chemical industry, metallurgy and power generation for environmental purposes M. Ginzburg, et al. 24. Briquetting of mining and metallurgical wastes V.A. Noskov, V.I. Bolshakov. 25. Neutralizing hazardous liquid waste in the coke industry V. Mikhailovshy. 26. Refractory materials and their influence on the ecological situation in the steel industry ecological and economic aspects V.

Peak exposures in aluminium potrooms: instrument development and field calibration

Aluminium smelter potrooms are unique in that workplace exposures to hydrogen fluoride (HF), sulfur dioxide (SO2), and particulate matter occur simultaneously for some tasks. The peak exposures to these contaminants are of increasing interest in discovering the etiology of respiratory health effects. While a variety of direct-reading instruments are available for sulfur dioxide and particulate matter, only a few exist for hydrogen fluoride. The sensors in these HF instruments have a cross-sensitivity to sulfur dioxide making it difficult to monitor HF in an environment that also contains SO2. To overcome this problem, we assessed the simultaneous use of two electrochemical instruments: one with a SO2 sensor that does not respond to HF and the second with a hydrogen fluoride sensor that responds to both HF and SO2 in a 1 : 1 ratio, termed 'total acid gas'. The difference in the response between the two instruments should indicate the HF concentration: [HF + SO2] minus SO2 equals HF. The performance characteristics of this sampling train were evaluated in the laboratory through the generation of both HF and SO2 with permeation tubes. The response and recovery times for the SO2 only instrument were acceptable (6 and 15 s, respectively), but the "total acid gas" instrument exhibited both slow response and slow recovery approaching three and six min. The association between the traditional integrated filter sampling method and the direct-reading instrument for SO2 is 0.80 (Spearman's rho). The use of the digital filter strengthens the association between the HF direct-reading instrument and the integrated samples from 0.41 to 0.68.

Genetic factors and asthma in aluminum smelter workers.

An asthma-like condition has been reported among aluminum smelter potroom workers. The pathophysiologic mechanisms and the causative agent involved are unknown. Inasmuch as gene polymorphisms are associated with asthma in the general population, the authors of this case-control study examined whether polymorphisms were associated with the development of potroom asthma. Genotyping was performed for the beta2-adrenoreceptor, high-affinity Ig (immunoglobulin) E receptor, and Tumor Necrosis Factor on potroom workers who developed a new asthma-like condition and on individuals who did not develop respiratory problems. No associations were found between potroom asthma case status and genotype. The asthma-like condition associated with potroom work remains poorly understood. Future investigations of genetic susceptibility and occupational asthma may provide pathophysiologic insights into these work-related conditions, but larger numbers of subjects will be required.

Investigation of the presence of amino and nitro polycyclic aromatic hydrocarbons in a Söderberg primary aluminum smelter.

An excessive risk of bladder cancer among Söderberg primary aluminum smelter potroom workers has been reported by several authors, and to date, a causal agent has not been identified. Certain nitro and amino polycyclic aromatic hydrocarbons (PAHs) are either known or suspected human bladder carcinogens, and their presence in this work environment would be cause for concern. In fact, one of these, 2-aminonaphthalene, has been found in both the air and the coal tar pitch used to fabricate process electrodes following an investigation in a Söderberg plant. During the present study, monitoring was conducted in a primary Söderberg aluminum smelter over a 3-week period using novel methods having very good specificity, reproducibility, and sensitivity. Results indicated that 1-aminonaphthalene and 2-aminonaphthalene and 1-nitronaphthalene and 2-nitronaphthalene were present at low parts-per-million levels in the coal tar pitch used to prepare the process electrodes. 1-aminonaphthalene and 2-aminonaphthalene were measured 40 cm above the electrolytic cells on days 1 and 2 of the investigation when the cells' ventilation systems had been shut down for repairs and maintenance. 2-aminonaphthalene was measured at concentrations ranging from 0.080 to 0.350 microg/m3. 1-nitronaphthalene and 2-nitronaphthalene, predominant in coal tar pitch, were not detected in any of the 43 air samples collected. A plausible explanation is their reduction to their respective amine during the electrolytic process. The routine screening of coal tar pitch used to prepare the process's electrode for both amino and nitro PAHs should be adopted by the aluminum industry as an effective means of controlling the presence of these carcinogenic pollutants in their workplace.

95/06574 Occupational PAH exposure: Urinary 1-hydroxypyrene levels of coke oven workers, aluminum smelter pot-room workers, road pavers, and occupationally non-exposed persons in Sweden

95/06574 Occupational PAH exposure: Urinary 1-hydroxypyrene levels of coke oven workers, aluminum smelter pot-room workers, road pavers, and occupationally non-exposed persons in Sweden

Occupational PAH exposure: urinary 1-hydroxypyrene levels of coke oven workers, aluminium smelter pot-room workers, road pavers, and occupationally non-exposed persons in Sweden

Polycyclic aromatic hydrocarbon (PAH) levels in air, and worker urinary 1-hydroxypyrene levels were studied in a coke oven, a Söderberg aluminium smelter pot-room, and during road-paving. Increased PAH exposure was shown to cause increased 1-hydroxypyrene excretion. Road-paving gave low PAH exposure, but resulted in a detectable elevated urinary 1-hydroxypyrene level. Background urinary 1-hydroxypyrene levels in office workers were determined, and a statistically significant difference between smokers and non-smokers was observed. It is suggested that urinary 1-hydroxypyrene can be used as biological exposure index for PAH exposure.