Aspectos técnicos e operacionais de desmontes com explosivo na mineração artesanal subterrânea

In the world today, due to the current high price of gold, thousands of artisanal small-scale mines operate without the financial or technical capacity to upgrade their production methods, often using equipment and working methods that were forsaken decades ago in the conventional mining industry. This article illustrates, with a practical example, that it is possible to achieve the modern requirements of quality, safety and productivity, while operating with mining equipment that basically possesses the same characteristics as that employed in the 1950s. The operation involved the excavation of a 6 meter long tunnel and over 25 stoping sections in both rock and concrete by drilling and blasting in an underground gold mine. The article describes how the main operational problems were overcome. An effective drilling pattern was designed in order to be easily achievable with the limited local equipment. The behavior of the local nitrate explosive was effectively predicted and managed. The interaction with the drilling teams was managed in order to determine a meeting point between their traditional working methods and the scientific view of the engineer. At the end of the article some general guidelines are proposed for the management of similar situations, in order to improve the efficiency, productivity and safety of drill and blast operations in small-scale mines

Data modeling for stochastic mine simulation

A simulação de lavra depende da utilização de dados coerentes e representativos da operação da mina. Esse trabalho propõe uma metodologia de modelagem de dados especificamente desenvolvida para simulação de lavra. A metodologia proposta foi aplicada a um estudo de caso de mina a céu aberto, onde dados do tempo de ciclo dos caminhões foram modelados para utilização em simulação de lavra. Os resultados da aplicação da metodologia indicaram que todas as variáveis modeladas aderiram a distribuições teóricas após o tratamento de dados, incluindo a remoção de outliers. O estudo identificou a necessidade do rastreamento das causas de inconsistências de dados, para o desenvolvimento de um processo de gestão de dados incorretos da operação de lavra.Mine simulation depends on data that is both coherent and representative of the mining operation. This paper describes a methodology for modeling operational data which has been developed for mine simulation. The methodology has been applied to a case study of an open-pit mine, where the cycle times of the truck fl eet have been modeled for mine simulation purposes. The results obtained have shown that once the operational data has been treated using the proposed methodology, the system variables have proven to be adherent to theoretical distributions. The research indicated the need for tracking the origin of data inconsistencies through the development of a process to manage inconsistent data from the mining operation

Modelo matemático e algoritmo de apoio para auxílio ao sequenciamento e à programação de lavra com alocação de equipamentos de carga

This paper focuses on the sequencing and scheduling problem of open pit mining,\ud with the allocation of loading equipment considering a medium-term horizon.\ud This study considers the existence of a heterogeneous loading equipment fleet and two\ud types of mineable material, namely ore or waste rock. For the mining of ore, the following\ud requirements are taken under consideration: the mixture quality, a crusher, the\ud processing plant capacity and a stockpile, called ROM stockpile. In this context, we\ud present a mathematical model in mixed integer linear programming, supported by an\ud algorithm that is responsible for moving the time horizon at each model run, aiming\ud to generate mining orders resolved with optimality. Together, these orders describe the\ud loading equipment mining plan.Esse trabalho tem seu foco no problema de sequenciamento e programação da\ud lavra em mina a céu aberto com a alocação de equipamentos de carregamento, considerando\ud um período de médio prazo. Nesse estudo, considera-se a existência de uma\ud frota heterogênea de equipamentos de carga e de dois tipos de materiais lavráveis,\ud sendo minério ou estéril. Para a lavra de minério, são contemplados requisitos de\ud qualidade da mistura, um britador, capacidade da usina de beneficiamento e uma pilha\ud de estoque, denominada pilha de ROM. Nesse contexto, apresenta-se um modelo\ud matemático em programação linear inteira mista, apoiado por um algoritmo responsável\ud por mover o horizonte de tempo, a cada execução do modelo, com intuito de\ud gerar ordens de lavra resolvidas com otimalidade. Juntas, essas ordens descreverão o\ud plano de lavra dos equipamentos de carga

Identification of additional risk loci for stroke and small vessel disease: a meta-analysis of genome-wide association studies

BACKGROUND: Genetic determinants of stroke, the leading neurological cause of death and disability, are poorly understood and have seldom been explored in the general population. Our aim was to identify additional loci for stroke by doing a meta-analysis of genome-wide association studies. METHODS: For the discovery sample, we did a genome-wide analysis of common genetic variants associated with incident stroke risk in 18 population-based cohorts comprising 84 961 participants, of whom 4348 had stroke. Stroke diagnosis was ascertained and validated by the study investigators. Mean age at stroke ranged from 45·8 years to 76·4 years, and data collection in the studies took place between 1948 and 2013. We did validation analyses for variants yielding a significant association (at p<5 × 10(-6)) with all-stroke, ischaemic stroke, cardioembolic ischaemic stroke, or non-cardioembolic ischaemic stroke in the largest available cross-sectional studies (70 804 participants, of whom 19 816 had stroke). Summary-level results of discovery and follow-up stages were combined using inverse-variance weighted fixed-effects meta-analysis, and in-silico lookups were done in stroke subtypes. For genome-wide significant findings (at p<5 × 10(-8)), we explored associations with additional cerebrovascular phenotypes and did functional experiments using conditional (inducible) deletion of the probable causal gene in mice. We also studied the expression of orthologs of this probable causal gene and its effects on cerebral vasculature in zebrafish mutants. FINDINGS: We replicated seven of eight known loci associated with risk for ischaemic stroke, and identified a novel locus at chromosome 6p25 (rs12204590, near FOXF2) associated with risk of all-stroke (odds ratio [OR] 1·08, 95% CI 1·05-1·12, p=1·48 × 10(-8); minor allele frequency 21%). The rs12204590 stroke risk allele was also associated with increased MRI-defined burden of white matter hyperintensity-a marker of cerebral small vessel disease-in stroke-free adults (n=21 079; p=0·0025). Consistently, young patients (aged 2-32 years) with segmental deletions of FOXF2 showed an extensive burden of white matter hyperintensity. Deletion of Foxf2 in adult mice resulted in cerebral infarction, reactive gliosis, and microhaemorrhage. The orthologs of FOXF2 in zebrafish (foxf2b and foxf2a) are expressed in brain pericytes and mutant foxf2b(-/-) cerebral vessels show decreased smooth muscle cell and pericyte coverage. INTERPRETATION: We identified common variants near FOXF2 that are associated with increased stroke susceptibility. Epidemiological and experimental data suggest that FOXF2 mediates this association, potentially via differentiation defects of cerebral vascular mural cells. Further expression studies in appropriate human tissues, and further functional experiments with long follow-up periods are needed to fully understand the underlying mechanisms

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Computer Support for the Management of Mine Water: An Object-Oriented Approach

The initial stages of the development of a computerised support system for mining engineers dealing with the management of mine water is described. The need for a software engineering methodology within the work group is discussed together with the perceived attractions of the socalled object model. The results of the preliminary analysis of the tasks necessary for the management of mine water in the prospecting, exploration, feasibility and early planning stages of the life of a mineral property are described, together with the engineering processes which should be considered in parallel and which might benefit from sharing common parts of a computerised support system. The paper may be of particular value to future novices in the field of object-oriented analysis and design. Introduction This is an account of the initial stages of the development of a computerised support system for mining engineers dealing with the management of mine water. Three of the authors are mining engineers..