Reciclagem de éter-aminas, utilizadas na flotação de minério de ferro, por meio da adsorção / Recycling of éther-amines, used in iron ore flotation, by adsorption

RESUMO O presente trabalho teve por objetivo verificar uma possível rota de reciclagem para as éter-aminas, utilizadas para aumentar a eficiência do processo de flotação catiônica reversa do minério de ferro. Estudou-se um método de separação físico-química utilizando TANFLOC como floculante. As águas de rejeito contêm, em sua maior parte, amina e sílica, e o objetivo desse método era separar a sílica do rejeito. A separação físico-química, porém, não foi eficaz, visto que o processo não foi capaz de flocular somente a sílica, floculando também parte da éter-amina. Foi avaliado também o processo de adsorção e, para tanto, utilizaram-se como materiais adsorventes a serragem Angelim e bagaço de cana-de-açúcar, ambos in natura. Esses materiais foram capazes de remover aproximadamente 95 e 90% de éter-amina, com capacidades adsortivas de 4,2 e 2,7 mg.g-1, respectivamente, utilizando massa de 1,5 g e estabelecendo tempo de equilíbrio de 30 minutos. Verificou-se que a eficiência de remoção é maior em pH próximo a 10. Pelos estudos termodinâmicos foi possível concluir, para a serragem, que o processo é termodinamicamente favorável e exotérmico. Para o bagaço de cana não foi possível analisar o comportamento termodinâmico. Além disso, o processo de dessorção permitiu recuperar em torno de 80% de éter-amina, além da possibilidade de regeneração e reutilização dos materiais adsorventes, o que mostra a viabilidade de reciclar a éter-amina pelo mecanismo de adsorção.

ABSTRACT The present work has the objective of investigating the possible recycling route for ether-amines, used for improving the efficiency of the process of iron ore's reverse flotation. A physical-chemical separation method has been studied using TANFLOC as flocculant. The wastewater contains, mainly, amine and silica, and the objective of this method was to separate the silica from the waste by flocculation. However, this method was not effective, as flocculation was not able to flocculate only silica, but also part of the ether-amine. Furthermore, the process of adsorption was assessed, and for this it was used as materials adsorbents Angelim's sawdust and sugar cane bagasse, both in natura, with which it was possible to remove approximately 95 and 90% of ether-amines, with adsorptive capacity of 4,2 and 2,7 mg.g-1, respectively, by using a mass of 1.5 g and a settling time of 30 minutes. It was verified that the removal efficiency is greater at a pH around 10. Thermodynamic studies were carried out and they were able to state, for sawdust, that this process is thermodynamically favorable and exothermic. In the case of sugar cane bagasse, it was not possible to analyze its thermodynamic behavior. In addition, the use of desorption revealed the possibility of regaining around 80% of the ether-amines. This proved that it is possible to recycle ether-amines by the adsorption mechanism.

Whole-body Vibration Exposure of Drill Operators in Iron Ore Mines and Role of Machine-Related, Individual, and Rock-Related Factors

BACKGROUND: This study aimed to assess the whole-body vibration (WBV) exposure among large blast hole drill machine operators with regard to the International Organization for Standardization (ISO) recommended threshold values and its association with machine- and rock-related factors and workers' individual characteristics. METHODS: The study population included 28 drill machine operators who had worked in four opencast iron ore mines in eastern India. The study protocol comprised the following: measurements of WBV exposure [frequency weighted root mean square (RMS) acceleration (m/s2)], machine-related data (manufacturer of machine, age of machine, seat height, thickness, and rest height) collected from mine management offices, measurements of rock hardness, uniaxial compressive strength and density, and workers' characteristics via face-to-face interviews. RESULTS: More than 90% of the operators were exposed to a higher level WBV than the ISO upper limit and only 3.6% between the lower and upper limits, mainly in the vertical axis. Bivariate correlations revealed that potential predictors of total WBV exposure were: machine manufacturer (r = 0.453, p = 0.015), age of drill (r = 0.533, p = 0.003), and hardness of rock (r = 0.561, p = 0.002). The stepwise multiple regression model revealed that the potential predictors are age of operator (regression coefficient beta = -0.052, standard error SE = 0.023), manufacturer (beta = 1.093, SE = 0.227), rock hardness (beta = 0.045, SE = 0.018), uniaxial compressive strength (beta = 0.027, SE = 0.009), and density (beta = e1.135, SE = 0.235). CONCLUSION: Prevention should include using appropriate machines to handle rock hardness, rock uniaxial compressive strength and density, and seat improvement using ergonomic approaches such as including a suspension system.

Minério de ferro, geologia econômica e redes de experts entre Wisconsin e Minas Gerais, 1881-1914 / Iron ore, economic geology and networks of experts between Wisconsin and the state of Minas Gerais, 1881-1914

O presente artigo trata da “descoberta” do minério de ferro brasileiro a partir de duas perspectivas. A primeira analisa a crescente ênfase das geociências em sua aplicação prática e em sua globalidade desde a segunda metade do século XIX. Enquanto no Brasil a geologia econômica foi integrada passo a passo às instituições do Estado, no nível global ela viveu momento de triunfo com o 11 o Congresso Geológico Internacional, em 1910. A segunda trata de uma rede social específica com papel decisivo na corrida pelo minério de ferro brasileiro: experts transnacionais movimentandose entre as lógicas do mercado e as da academia. O artigo mostra a importância das negociações locais na incorporação do subsolo mineiro ao espaço global de mineração.

This article deals with the “discovery” of Brazilian iron ore from two perspectives. The first examines the increasing emphasis of the geosciences and their practical application and global reach since the second half of the nineteenth century. While in Brazil economic geology was integrated step by step into state institutions, at the global level it experienced its moment of triumph with the 11th International Geological Congress in 1910. The second deals with a specific social network with a decisive role in the race for Brazilian iron ore: with transnational experts juggling between the logic of the market and that of the academy. The article reveals the importance of local negotiations in the incorporation of the subsoil of Minas Gerais into the global space of mining.

Morbidity Among Iron Ore Mine Workers in Goa.

This study was carried out among workers from an open-cast iron ore mine in South Goa with an objective to assess morbidity among these workers. Investigations were carried out at the Occupational Health Service Clinic of the mining company. Nearly 0.6% workers had pneumoconiosis, 3.2% had abnormal spirometry fi ndings, 38.16% had hearing loss and 27.7% had defective vision respectively. The prevalence of other chronic diseases were as follows: diabetes 5.1%, hypertension 8.3%, dyslipidemia 37.5% and polycythemia 12.7% respectively. Since the fi ndings were not compared with the pre-placement records and as most of the workers are young with duration of exposures <10 years, relationship cannot be defi nitely determined. The study fi ndings are suggesting an association between the occupation in mining with pneumoconiosis, compromised lung function and hearing loss. However for the other fi nding further analytical studies are required to see for any association. Airborne respirable dust survey and noise monitoring studies also need to be carried out.