A cada dia aumenta a preocupação com relação às condições de exposição ocupacional dos trabalhadores, nos mais diversos setores, tanto em nível da análise dos postos de trabalho quanto das implicações legais decorrentes destas. No presente estudo, sobre as atividades desenvolvidas em instalações de britagem, objetivou-se criar um modelo para analisar, avaliar e propor melhorias para o funcionamento destas instalações, com ênfase na saúde e em segurança dos trabalhadores. Utilizou-se para tal uma metodologia compreendendo: visitas in loco, questionários, análise dos postos de trabalho e da vivência, ou seja, do conhecimento dos envolvidos na operação. Como resultado, obteve-se um modelo que considera os diversos fatores intervenientes na implantação de instalações de britagem (ligando os fatores relacionados aos aspectos: técnicos, jurídicos e ocupacionais). Foram verificadas especificamente possíveis melhorias a serem introduzidas na empresa, bem como, de forma mais ampla, a constatação do descaso ou desconhecimento das empresas quanto aos diversos aspectos que norteiam esta atividade, aspectos psicossociais e comportamentais dos trabalhadores. / Day after day we are becoming more and more concerned about workers´ occupational exposition conditions in several sectors from workplace analysis level to their legal implications. In the present study about activities developed in crushing plant facilities we targeted the creation of a model to analyze, assess and propose improvements for these facilities functions focused on health and on workers’ safety. Therefore, we used a methodology which comprehends the following: in loco visits, questionnaires, workplace analysis, its life mode, that is, the knowledge of the ones involved in the operation. As a result we obtained a model which considers the several interfering factors in the implementation of crushing plant facilities (linking factors related to occupational, juridical and technical aspects). We verified specifically possible improvements to be introduced in the company as well as, in a broader scope, we realized a neglect or ignorance of companies regarding the several aspects which rule this activity such as worker´s psychosocial and behavioral aspects.

A cada dia aumenta a preocupação com relação às condições de exposição ocupacional dos trabalhadores, nos mais diversos setores, tanto em nível da análise dos postos de trabalho quanto das implicações legais decorrentes destas. No presente estudo, sobre as atividades desenvolvidas em instalações de britagem, objetivou-se criar um modelo para analisar, avaliar e propor melhorias para o funcionamento destas instalações, com ênfase na saúde e em segurança dos trabalhadores. Utilizou-se para tal uma metodologia compreendendo: visitas in loco, questionários, análise dos postos de trabalho e da vivência, ou seja, do conhecimento dos envolvidos na operação. Como resultado, obteve-se um modelo que considera os diversos fatores intervenientes na implantação de instalações de britagem (ligando os fatores relacionados aos aspectos: técnicos, jurídicos e ocupacionais). Foram verificadas especificamente possíveis melhorias a serem introduzidas na empresa, bem como, de forma mais ampla, a constatação do descaso ou desconhecimento das empresas quanto aos diversos aspectos que norteiam esta atividade, aspectos psicossociais e comportamentais dos trabalhadores. / Day after day we are becoming more and more concerned about workers´ occupational exposition conditions in several sectors from workplace analysis level to their legal implications. In the present study about activities developed in crushing plant facilities we targeted the creation of a model to analyze, assess and propose improvements for these facilities functions focused on health and on workers’ safety. Therefore, we used a methodology which comprehends the following: in loco visits, questionnaires, workplace analysis, its life mode, that is, the knowledge of the ones involved in the operation. As a result we obtained a model which considers the several interfering factors in the implementation of crushing plant facilities (linking factors related to occupational, juridical and technical aspects). We verified specifically possible improvements to be introduced in the company as well as, in a broader scope, we realized a neglect or ignorance of companies regarding the several aspects which rule this activity such as worker´s psychosocial and behavioral aspects.

A cada dia aumenta a preocupação com relação às condições de exposição ocupacional dos trabalhadores, nos mais diversos setores, tanto em nível da análise dos postos de trabalho quanto das implicações legais decorrentes destas. No presente estudo, sobre as atividades desenvolvidas em instalações de britagem, objetivou-se criar um modelo para analisar, avaliar e propor melhorias para o funcionamento destas instalações, com ênfase na saúde e em segurança dos trabalhadores. Utilizou-se para tal uma metodologia compreendendo: visitas in loco, questionários, análise dos postos de trabalho e da vivência, ou seja, do conhecimento dos envolvidos na operação. Como resultado, obteve-se um modelo que considera os diversos fatores intervenientes na implantação de instalações de britagem (ligando os fatores relacionados aos aspectos: técnicos, jurídicos e ocupacionais). Foram verificadas especificamente possíveis melhorias a serem introduzidas na empresa, bem como, de forma mais ampla, a constatação do descaso ou desconhecimento das empresas quanto aos diversos aspectos que norteiam esta atividade, aspectos psicossociais e comportamentais dos trabalhadores. / Day after day we are becoming more and more concerned about workers´ occupational exposition conditions in several sectors from workplace analysis level to their legal implications. In the present study about activities developed in crushing plant facilities we targeted the creation of a model to analyze, assess and propose improvements for these facilities functions focused on health and on workers’ safety. Therefore, we used a methodology which comprehends the following: in loco visits, questionnaires, workplace analysis, its life mode, that is, the knowledge of the ones involved in the operation. As a result we obtained a model which considers the several interfering factors in the implementation of crushing plant facilities (linking factors related to occupational, juridical and technical aspects). We verified specifically possible improvements to be introduced in the company as well as, in a broader scope, we realized a neglect or ignorance of companies regarding the several aspects which rule this activity such as worker´s psychosocial and behavioral aspects.

African copper PLC’s flagship is the copper producing Mowana mine located 129 km from Francistown in the North-Eastern part of the Republic of Botswana. The processing operation at Mowana is a standard flotation plant designed to produce copper concentrates from oxide, supergene, and sulphide ores. The expected average output of 16.2 tons per hour of copper concentrates has never been attained since plant commissioning. The major bottleneck has been established to be located around the crushing circuit of the Mowana production chain. The major hypotheses of this research are that performance in a crushing plant is adversely influenced by moderate and discrete changes in the process. The ultimate objective is to develop a dynamic process simulator, administered in Simulink/MATLAB® background, for application in the design of a control model utilising two crusher variables and a self-tuning control algorithm. In this research work, a process model describing the dynamic operation of an Osborn 57S gyrasphere cone crusher is investigated. Modelling of the Mowana crushing circuit is carried out by combining the steady-state and dynamic components of the crushing equipment in the Simulink/Matlab® environment. Eccentric speed (ES) and closed-side setting (CSS) are amongst the important inputs to the models. The rest of the inputs (crusher power, crusher cavity level, federate, pulley diameters, liner wear measurement, number of teeth of the pinion and bevel gear) are extracted from the data collected across the Mowana mine crushing circuit. While it has been demonstrated that the crusher CSS is the most influential controllable parameter, it has also been demonstrated that crusher capacity and power can be used effectively to optimise the circuit. The use of crushing power and cavity level control is suitable for the crushing circuit since the crushers are running on a constant ES and the CSS is set and reset manually. The outcome of the study presents an insight into the optimization of the Mowana mine crushing circuit through the design of a self-tuning controller for the cone crusher and for prototyping, parameters of a PID controller were determined in the Simulink/MATLAB® environment. The simulation involved the optimisation of the control model as a function of the cavity level of and the power drawn by the cone crusher. A self-tuning control algorithm at PLC and SCADA level of control was then tested. This formed the simulations and training platform. The outcome of the simulations carried out in this research needs to be validated against the real Mowana crushing process control upgrade. This will then inform the modifications and recommended crusher motor resizing exercise to be implemented. / Electrical and Mining Engineering / M. Tech. (Engineering: Electrical)