Raul Oliveira Neto

Modeling and planning of bentonite clay mining: a case study at Bañado de Medina, Melo, Uruguay

Mining planning and its correct sequencing are essential to facilitate the exploitation of minerals both economically and environmentally, thus ensuring the feasibility of the mining in operational and economic terms. The small geological complexity or the low aggregate value of a mineral deposit tends to result in the planning stages being neglected, so the mining begins without the necessary detailing or it is only scheduled for a short period of time. Thus, in order to ensure a sustainable sequence of operations, and to predict the environmental impacts caused by mining activities and suggest options that would allow the establishment of mitigation measures for these impacts, the feasibility of the technical and economic utilization was evaluated for an occurrence of bentonite in the Banado de Medina deposit located in the Department of Cerro Largo, Uruguay, respecting the local environment in the process so as to give the project a strong character of sustainability.

AVALIAÇÃO DE IMPACTO RELACIONADO COM RUÍDO E VIBRAÇÃO EM PERÍMETRO URBANO

With economic and population growth in recent decades, it has been possible to observe an increase of vehicles in urban areas, and associated with it an increase in health problems caused by the daily impact of equipment and vehicles in cities. Generally, the main impacts realized by the population are the vibration and noise, often caused by the intense traffic of vehicles, as well as the operation of mechanical equipment in industries or construction. Thus, this work aims to make a comparison between data that are generally obtained in the mining environment with data from urban area, both collected through seismic monitoring. The monitoring was developed in the urban area of Cacapava do Sul, and despite the noise levels observed in mining environment were significantly higher, some vibration levels collected in urban areas were equally high. This work shows that several factors may have influence on the monitoring, for example how to collect data or setup the equipment, and that many complaints attributed to mining operations may have actually been several sources within the city limits.

METODOLOGIA DE AVALIAÇÃO AMBIENTAL NA ANÁLISE DE ALTERNATIVAS LOCACIONAIS DE PILHAS DE ESTÉRIL

This work use an environmental planning methodology , as an aid to the analysis of location alternatives for disposal of overburden to be generated during the development and operation phases of the future of pit mine phosphate Tres Estradas. Applying technical guidance, present in the NBR 13029 of ABNT , with minimum character of the impacts on the environment by applying weights to environmental parameters for each alternative , and comparing them and introducing a hierarchy of alternatives, the study takes to the general mitigation and compensation measures proposition, which should be deepened after choosing the best alternative for the company . After this application of the proposed methodology at work, we came to the conclusion for one of the alternatives that was better punctuated , according to the established criteria , which was a stack 4 between the four alternatives set out in the project.

METODOLOGIA DE ANÁLISE QUANTITATIVA DE VOLUME DE ROCHA DESMONTADO UTILIZANDO SOFTWARE DE MINERAÇÃO

This work presents a quantitative analysis methodology of blasted rock volume. Field topographic information was collected regarding the blasting of mining benches in a limestone mine, and these data plus the blast holes layout were used to generate a digital model of the benches with the Micromine software. Besides allowing the visualization of the 3D wireframe models with the spatial arrangement of the blast holes, it was possible obtain the volumes of the solids that is the actual rock volume generated by the blasting, and compare it with the estimated volumes, based on the estimated dimensions of the benches only. Despite the minor discrepancies observed in terms of volume, the results showed significant improvement on the visualization aspects and were useful to detect problems related with the blasting plan as burden distance above or below the optimal and deviations of blast holes.

LEVANTAMENTO DAS DESCONTINUIDADES E AVALIAÇÃO DA ESTABILIDADE DE TALUDES DA MINA DO MANGUEIRÃO

The study and control of slope stability have grown greatly in recent decades, so the quality and the reliability of the results of an analysis of stability are very important because they provide savings for the enterprise and security for workers. This article aims to address the geological and geotechnical aspects considered most important for the stability of slope excavation in rock masses. To achieve this goal, a review of the characteristics of discontinuities was held as spacing, orientation, opening, filling, percolation and roughness fractures. Through scanlines, was made histogram frequency of these discontinuities, stereographic projections in the software stereonet9 and identification of the main families of discontinuities, because the main determinants of failure modes in rock masses are these structures. To do so, seven slopes were selected, with evidence of instability, which were subjected to a series of field studies to obtain the parameters necessary to reach the minimum safety factor. In this way situations were simulated eight 45 ° intervals with mining advance, that in three of them were obtained satisfactory results, given the expectation of work.

RECUPERAÇÃO AMBIENTAL NA DISPOSIÇÃO DE ESTÉRIL EM MINERAÇÃO DE CALCÁRIO

Os estereis e os rejeitos sao os principais residuos gerados pela mineracao, merecendo atencao no que diz respeito a seu correto manuseio e destinacao. Apesar da lavra de calcario, comumente, compreender operacoes unitarias basicas, ao longo dos anos movimenta grandes volumes de esteril que e depositado em pilhas. Neste contexto, o presente trabalho visa avaliar e propor melhorias aos aspectos construtivos da pilha em estudo, identificando os impactos ambientais e propondo as medidas mitigadoras e compensatorias cabiveis. Para obtencao dos dados, foi realizado levantamento topografico e processamento dos mesmos, primeiramente na planilha Excel e posteriormente nos softwares Surfer e Autocad. Na avaliacao de impacto ambiental foi utilizada a matriz de Leopold e parâmetros da ISO 14001, definindo-se criterios de hierarquizacao da significância dos impactos. O levantamento geometrico realizado apontou problemas quanto a conformacao de taludes e bermas, apesar de fatores como altura maxima e conservacao de areas de preservacao permanente estarem de acordo. Quanto a estabilidade, os valores de fator de seguranca estao, em media, de acordo com a legislacao, que determina um minimo de 1,5, entretanto, alguns taludes intermediarios nao alcancam este valor. Ha, tambem, zonas que nao atendem as boas praticas propostas, como ângulo de talude inferior a 36o, porem, em toda a pilha nao sao verificados sinais de ruptura. A avaliacao de impacto ambiental realizada constatou que 50% dos impactos sao graves e 50% sao medios, aos quais foram propostas medidas mitigadoras e compensatorias e planos de acao e monitoramento. Como conclusao, pode-se dizer que a pilha atende somente em parte as normas e boas praticas, sendo de fundamental importância a implantacao das medidas e de plano de acao propostos.

DIAGNÓSTICO E MODELOS DE PREVISÃO DE NÍVEIS DE RUÍDO E VIBRAÇÃO EM DESMONTE DE ROCHAS COM EXPLOSIVOS

No desmonte de rochas com explosivos, somente de 20 a 30% da energia gerada e de fato utilizada na fragmentacao e movimentacao do macico rochoso, sendo que o restante desta energia e dissipado como calor, ruido e vibracao. Enquanto dificilmente se pode mensurar ou atuar na minimizacao da energia transmitida sobre a forma de calor, o ruido e a vibracao podem ser monitorados e correlacionados tanto com a carga maxima de explosivo iniciada num mesmo instante, quanto com a distância da fonte geradora. Desta forma, modelos matematicos de atenuacao podem ser obtidos, permitindo a previsao dos niveis de vibracao e ruido para cada desmonte, bem como a modificacao dos parâmetros dos planos de fogo de maneira a nao ultrapassar os limites maximos permissiveis para ruido e vibracao estabelecidos pelas normas reguladoras (NBR 9653/2005 da ABNT e NRM 16 do DNPM). Neste sentido, desde 2013 campanhas sucessivas de monitoramente tem sido realizadas nas operacoes de lavra de calcario do municipio de Cacapava do Sul, utilizando microssismografos de engenharia a certa distância do desmonte, sendo que esta e mensurada atraves do sistema de coordenadas UTM, considerando indiferente o desnivel de altitude de ate 6 metros. Na primeira campanha realizada, 30 eventos monitorados permitiram constatar niveis bastante baixos de vibracao, resultado da atenuacao promovida pela grande heterogeneidade do macico. No entanto, a mesma campanha apontou a ocorrencia sistematica de valores elevados de ruido, varios inclusive ultrapassando os 134 dB, limite maximo permitido pelas normas. Em funcao deste diagnostico e que foi concebida a segunda campanha de monitoramento, tendo como objetivo aferir a qualidade do modelo de previsao anteriormente obtido verificando a resposta do ruido a diferentes alternativas tecnicas, como a cobertura dos cordeis detonantes com material areno-argiloso ou a substituicao dos cordeis utilizados (NP10) por outros com menor quantidade de explosivo por metro linear (NP05) e a pesagem das cargas durante a etapa de carregamento dos furos, com o intuito de reduzir os niveis de ruidos. Porem, observou-se que os niveis de vibracao estavam abaixo dos limites estabelecidos pelas normas e que os valores de ruido, mesmo com as modificacoes propostas, permaneceram em patamares bastante elevados. Logo, foi possivel constatar que as principais causas relacionadas com os niveis de ruido sao: a grande extensao de cordel exposto, ligando as bancadas a serem detonadas com blocos ou matacos remanescentes de desmontes anteriores, o desmonte secundario propriamente dito destes matacos e a ejecao de gases em altissima velocidade pela boca dos furos, pelo fato de ser utilizado material inadequado como tampao e da acao do acessorio utilizado ao longo dos furos. Ja a pesagem das cargas de cada desmonte monitorado mostrou diferencas significativas em relacao a pratica das empresas de estimar a carga em funcao dos parâmetros geometricos do plano de fogo. Como a carga maxima por espera utilizada nos modelos de previsao da primeira campanha foram estas cargas estimadas, este modelo nao e adequado e os dados da segunda campanha permitiram a obtencao de modelos de previsao com um grau de confiabilidade muito maior.

ANÁLISE E INTERPRETAÇÃO DE PARÂMETROS DE QUALIDADE DE MACIÇO PARA PROPOSIÇÃO DE MODELO GEOMECÂNICO

Before lauching any mining enterprise, whether open pit or underground, must have knowledge of rock mass geomechanical characteristics, which the work will be developed. The geomechanical classification systems are used to obtain information about these characteristics. These systems gather the necessary information and propose an index for rock mass qualifying. This article presents the methodology used on a rock mass qualifying for a lead and zinc deposit, through the classification system Rock Mass Rating (RMR), to propose a geomechanical model. Through the analysis of 50 drill holes with its geological logs it was possible to create the deposit geological model, recognizing the units present in the study area. Were identified 4 units: sandstone, conglomerate, rhythmite and ore. In addition, information was collected regarding the 6 parameters, which RMR is based, on drill holes. After RMR values being determined over all drill holes, they were estimated within each unit by the indicator kriging. From the estimation results was possible to obtain the geomechanical model. In the proposed geomechanical model was observed the predominance of class II (good rock) in all units. In the model base predominated class III and IV (fair rock and poor rock respectively) due to the presence of breccia.

AVALIAÇÃO DA GESTÃO INTEGRADA DE RESÍDUOS SÓLIDOS URBANOS NO BRASIL

Management of urban municipal waste has become an increasing problem for governments in developing countries, in the last decades. Not only the developing countries but also the developed ones have introduced restrictive environmental legislations with the objective of optimization of waste treatment and waste disposal programs. The main objective of the present paper is to investigate the real situation of this scenario and in developed countries, showing the results and tracing a parallel comparative and critical. Are transcribed and analyzed the data obtained at each stage of an Integrated Solid Waste Management – GIRSU. Important findings are reported, such as the high level of investment by developed countries, inverted in awareness campaigns for implementing a GIRSU effective, as well as remarkable contrasts between recycling rates in Brazil than differential block of this others countries, that is, 2% and 20%, respectively, in the total amount of waste generated. The final assessment is that the big difference is about economic incentive policy of the block of developed countries in terms of subsidies, compared to the Brazilian case.

CONTROLE E PREVISÃO DE NÍVEIS DE RUÍDO E VIBRAÇÕES GERADOS PELO DESMONTE DE ROCHAS COM EXPLOSIVOS

Air blast and ground vibrations generated by rock blasting have become a major legal and technical problem, mainly due the growing of the cities to the neighborhood of mines and quarries. For many people, the main environmental impacts associated with mining are those generated by rock blasting, and there is a real risk in handling explosives since just around 20-30% of the explosives energy is used to fragment and throw the rock. But the effects of explosives can be precalculated and predicted quite accurately, according the regulations for the use of explosives which are meant to be such a safeguard against accidents. These rules or laws establish that it is necessary to carry out a risk analysis in order to determine, first, what size vibrations the environment will accept and second, how large a charge can be blasted at certain distance without exceeding that vibration or noise limits. This risk analysis has been made in the limestone mines of Cacapava do Sul involving a careful examination of the factors that can affect the blasting operations. At the same time, a mathematical model has been developed in order to reliably predict the noise and vibration levels for a determined distance in the vicinity of the blasting place.