Wilson Siguemasa Iramina

Principais normas e recomendações existentes para o controle de vibrações provocadas pelo uso de explosivos em áreas urbanas: parte II

Blasting requires control measures related to structural damage to buildings and environmental impacts like ground vibrations, noise, flyrock and air blast. The use of explosives is controlled by federal and state regulations, which involve measurement of parameters to evaluate probable damage in buildings and other type of constructions. In urban areas, the peak particle velocity (PPV) associated with ground vibration and expressed in mm/second, is the best parameter to evaluate possible structural damages. Worldwide legal limits vary from a low 2 mm/s for historical buildings to a high 150 mm/s for reinforced concrete. Most of the regulations consider peak particle velocity and frequency as a double damage parameter. Some regulations were elaborated with an experimental database, involving different types of construction and building materials. Others were proposed using empirical data. Both regulations present conservative values. This paper presents a review of the most important European regulations for blasting activities, presenting the state of the art in this area. A second part of paper will show American Regulations and the norms of other continents.

Mining as a tool for reclamation of a Degraded Area

Any human activity causes environmental degradation, resulting in a continu ous deterioration of environmental quality (water, air or soil). While mining is also an activity that causes degradation of the environment, it is essential for the continuity of life as it is known. On the other hand, paradoxically, by keeping life in this way, we are contributing to its cessation. This leads us to look for alternatives to reduce the impact of mining activities. The Reclamation of degraded areas may be an alternative, as it can mitigate the current picture of continuous environmental degradation. However, Degraded Areas not always follow a mining operation. This article

Fatal Accidents and Rockfalls in Peruvian Underground Mines

Developing countries depend on primary industries such as the mineral industry. Peru is one of the most important mineral producers in the world and political and economic stability have brought great interest in mining in the past 20 tears. In the Peruvian economy, about 6% of Gross Domestic Product (GDP) and over 50% of exports are provided by mineral commodities. The Peruvian mining industry has become aware of the need to improve health and safety of the people involved in the industry. Peruvian regulations on mining health and safety, approved in 2001, are intended to protect human life, promote health and safety and reflect the culture of prevention related to incidents and accidents. A decrease in the number of mining accidents in recent years has been perceived but the mortality rate is still high when compared to traditional mining countries. Official reports state that the fundamental causes for the accidents are related to personal and work factors, as well as human errors. Therefore an accurate identification of causes is required for better safety and health management systems. From 2000 to 2007 there were 433 fatal accidents with 499 fatal victims in Peruvian mining industry and the majority of these accidents were caused by rockfalls in underground excavations. In addition, a study of rockfalls in 2007 has brought information about where (in the mine) these accidents occurred and who were the victims. Human errors, personal factors and non-complying procedures have contributed to these accidents.

Iso-velocity maps. A vibration control tool in quarries

Urban growth around mining areas has brought problems such as neighborhoods discomfort due to blasting vibrations, which can cause structural damage to the houses, dust and atmospheric overpressure. In Brazil, environmental restrictions are increasingly rigorous and seismic monitoring is required as an environmental control measure. This study aims to analyze a methodology for application of iso-velocity maps in quarries located in urban areas and evaluate options for building iso-velocity maps. This work was performed in a quarry located in the State of Sao Paulo and four blastings were monitored. All blastings had similar features and they were evaluated in the same bench. For each equation, directional, scaled-distance parameters were estimated and different iso-velocity maps were made and compared. It is concluded that geophone disposition must adjust to the monitoring purposes. Eight to fifteen aligned geophones are adequate for a scaled-distance curve. Sixty-four or more geophones, spatially and homogeneously distributed, can generate an iso-velocity map concerning a single blasting. High variability of rock mass features seems to prevent obtaining good results when the seismographs are not homogeneously distributed surrounding the blasting.

Identificação e controle de riscos ocupacionais em pedreira da região metropolitana de São Paulo

Crushed stone mining is the third largest mining economy in Brazil, where almost half is produced in the Sao Paulo metropolitan region. The segment registers the highest number of accidents among the extractive industries, which justifies the concern with workers’ health and safety and the importance of controlling occupational hazards. Since 2002, the NR-22 Standard (NR-22: Occupational Health and Safety in Mining) makes compulsory the elaboration of a Risk Management Program that identifies risks and establishes control measures. Considering the crushed stone mining industry’s importance to the state, this paper evaluates and discusses the risks identified in unit operations during the production process of crushed stone in an open pit mine in order to propose control measures for the development of the Risk Management Program. Although this study refers to a specific quarry, it can be applied to other mines from the same sector, since some considerations are made regarding differences in manufacturing processes. The research was based on the identification of the main risks associated with drilling, blasting, load & haulage, crushing and screening through field measurements of some hazardous agents, together with company reports. The results contributed to the choice of the appropriate control measures for the improvement of workers’ health and safety conditions.

Análise de acidentes fatais na mineração: o caso da mineração no Peru

A mineracao e uma das atividades industriais que oferecem maior risco; embora nos ultimos anos tenham-se percebido reducoes na taxa de lesoes e acidentes, o seu numero e grau de severidade ainda sao elevados. As causas fundamentais para as altas taxas de acidentes podem ser atribuidas as condicoes inseguras e os atos inseguros; nesse cenario, a identificacao de problemas de seguranca visando a proposta de solucoes efetivas para gerenciar riscos faz-se necessaria. Por outro lado, a dependencia de paises em desenvolvimento por industrias primarias como a mineracao e evidente. Na economia peruana, aproximadamente, 16 % do PIB e mais de 50 % das exportacoes referem-se a esta industria, destacando sua posicao competitiva na mineracao mundial. Esse artigo analisa os acidentes fatais na mineracao peruana, desde o ano 2000 ate maio de 2008. A fonte de informacao primaria foi o registro de acidentes, disponibilizado pelo Ministerio de Energia e Minas do Peru; identificando-se varios tipos de acidentes com destaque para aqueles provocados por queda de rochas em minas subterrâneas. A maioria das vitimas sao trabalhadores de empresas terceirizadas prestadoras de servicos especializados. Os resultados mostram que a mineracao subterrânea tem maiores riscos do que a de superficie.

Comparing blast-induced ground vibration models using ANN and empirical geomechanical relationships

Blasting remains as an economical and reliable excavation technique, but there are some environmental shortcomings such as the control of blast-induced vibration. The impacts of vibration over surrounding communities in a blast area have been investigated for decades and researchers have been using a myriad of empirical predictive attenuation equations. These models, however, may not have satisfactory accuracy, since parameters associated to geomechanical properties and geology affect the propagation of seismic waves, making vibration modeling a complex process. This study aims for application of an Artificial Neural Network (ANN) method and Geomechanical parameter relationships to simulate the blast-induced vibration for a Brazilian mining site and then compare them to the traditional approach. ANN had the best performance for this mine despite having demanded large datasets (as much as for the traditional approach), while geomechanical parameters like RQD and GSI may be used to deliver a fair approach even without seismic data. Also, ANN methods may be useful in dealing with a large amount of information to facilitate the simulation process when combined with other methods. Therefore, alternative prediction methods may be helpful for small budget mining operations in planning and controlling blast-induced vibration and helping mining in urban areas becoming a more sustainable activity.

Radon in Brazilian underground mines

Radon is a chemically inert noble radioactive gas found in several radioactive decay chains. In underground mines, especially those that contain or have contained ores associated with uranium-bearing minerals, workers might be exposed to high levels of radon and its decay products (RDP). This work aims to investigate whether the exposure of workers to radon gas and its progeny has been evaluated in Brazilian non-uranium and non-thorium underground mines. Any such results and control measures undertaken or recommended to maintain concentrations under Brazilian occupational exposure limits (OELs) are documented. The methodology we adopted consists of three main phases. The first was an extensive bibliographical survey of the concentration levels of radon and RDP, as well as the radiation dose estimates, considering measurements made heretofore by various Brazilian researchers and exhibiting original measurement work undertaken by the one of the authors (mine O). In the second phase, the values obtained were compared with OELs. In the third phase, any control measures undertaken in mines with high exposure of workers to radon and its progeny were verified, and the adopted controls were determined. Radon concentration data obtained from 52 campaigns in 40 underground mines were analyzed. The results show that assessment of the exposure of workers to radon and its progeny was undertaken in many mines at least once, and that radon levels in 62.5% of the mines, when visited for the first time, were below the Brazilian OELs. As expected, the main control measure adopted or recommended was improvement of the ventilation system.

Using a noise monitoring station in a small quarry located in an urban area

Mining plays an important role in Brazilian exports. On the other hand, large urban centers like São Paulo, with approximately 21 million inhabitants, also demand an increasing domestic consumption of natural resources, such as construction aggregate. There are many quarries located in the surroundings of urban centers in Brazil, competing with the growth of urbanized areas. Such proximity leads to a series of conflicts involving quarries and surrounding communities, where the increase in noise levels is highlighted. Operations in quarries, in general, are intermittent. Noisier equipment, such as drilling rigs and primary crushers, operates only a few hours during the day, while other operations, such as screening and secondary and tertiary crushing, are more constant. This paper presents a study carried out in a quarry located near São Paulo, where in addition to conventional short term noise measurements at surrounding receptors, one noise monitoring station was installed, allowing to identify the noisiest moments during the quarry operating time. Through data transmitted by wireless technology, it was possible to follow the noise variations emitted from mining activities in real time and observe the noisiest events that were recorded for events that exceeded the established standards. A mobile application associated to this monitoring station facilitated the quarry’s manager and employees to access immediately the monitoring information. Therefore, by using this system, it was possible to evaluate the effectiveness of noise reduction measures already taken and indicate what steps still need to be held.

Financial Compensation for the Use of Mineral Resources at the Minas Gerais State – Brazil

The Financial Compensation for the use of Mineral Resources - CFEM, is a compensation for the mining activity in the municipalities where it is allocated. This study shows the importance of CFEM in the State of Minas Gerais - Brazil, where the mining activity is very important. The importance of CFEM is on its application on the counties, as it must be used in projects that bring improvements on the life conditions of the population. Usually, the HDI – Human Development Index of the municipalities where mining projects are developed is higher than the HDI of the State in which such projects are located. However, the correct management of this compensation must be reconsidered focusing on the development of local communities. It is important to highlight that, besides CFEM, the mining companies develop many other projects related to culture, education, sports, among others in the communities where they are located, bringing benefits for the population. With the new mining code, some changes in CFEM are expected, mainly in its calculation and in the percentages of some mineral resources taxes. Besides, a better distribution of the values is being considered, mainly associated to surrounding counties which are also affected by the mining activities. Thus, CFEM is understood as an important compensation for the mining activity that can bring many benefits if well applied and managed.