REGIME DE TRANSPORTE DE POLPA DE MOINHO ISAMILL EM ESCALA DE LABORATÓRIO

O moinho IsaMill tem se mostrado eficiente em etapas de remoagem. Isso ocorre porque os moinhos deste tipo permitem a utilização de corpos moedores muito pequenos em relação a outros tipos de moinhos, notoriamente o moinho tubular de bolas e o VertiMill. Corpos moedores de pequeno diâmetro implicam em eficiência maior na moagem de partículas finas. Neste trabalho foram realizados quatro ensaios de moagem contínuos, em condições diversas, com duas amostras de minério de cobre com granulação distinta. A determinação da distribuição de tempos de residência da fase líquida realizou-se com um ácido como traçador e medidas de pH no produto do moinho de laboratório de um litro. Os resultados obtidos indicam que o moinho IsaMill de laboratório apresenta um padrão de distribuição de tempo de residência de fluxo pistão e deverá se comportar similarmente a um moinho de barras do ponto de vista de transporte

Modelagem e simulação de circuito de moagem através da determinação dos parâmetros de quebra e da energia específica de fragmentação.

Exportado OPUSMade available in DSpace on 2019-08-09T21:24:14Z (GMT). No. of bitstreams: 1 ppgengmetalurgicaminas_douglasbatistamazzinghy_dissertacaomestrado.pdf: 3647494 bytes, checksum: b2b117ff0e4c9f8b675d0bf76d07782b (MD5) Previous issue date: 9A otimização de circuitos industriais de moagem tem sido realizada com sucesso, utilizando modelos matemáticos que relacionam dados industriais com parâmetros de quebra e energia específica de fragmentação determinados em laboratório.Neste estudo, é apresentado um exemplo clássico da utilização desta metodologia, onde os parâmetros de quebra e dados de consumo específico de energia foram determinados em ensaios laboratoriais, utilizando um moinho dotado de um sensor de torque.O material em estudo é um minério de ouro contendo sulfetos, que é fragmentado através de um circuito fechado de moagem de bolas e classificação realizada por hidrociclones.Várias campanhas de amostragens foram realizadas com o objetivo de fechar um balanço de massas e fornecer material para a determinação dos parâmetros de quebra em laboratório.Através dos dados levantados em laboratório foi possível prever, por simulação, o comportamento do circuito frente a alterações de variáveis operacionais específicas. Como resultado, as alterações propostas podem possibilitar ganhos de produtividade e de aproveitamento energético.The optimization of industrial grinding circuits has been accomplished with success,using mathematical models that relate industrial data with breakage parameters and specific energy of fragmentation determined in the laboratory. In this study, a classical example of the use of this methodology is presented, where the breakage parameters and data for the specific energy consumption were established by laboratory tests using a grinding mill equipped with a torque sensor. The material in this study is a gold sulfide ore ground in a closed ball mill circuit thatutilizes hydrocyclones. Several sampling campaigns were carried out with the objective to provide a mass balance and to produce sufficient material for the determination of the breakage parameters in the laboratory. The data obtained in the laboratory allowed for estimating, by simulation modeling, the behavior of the circuit based upon the changes of specific operation variables. The proposed changes should make it possible to increase productivity and save energy in the ball mill grinding circuit

ARE THERE SIGNIFICANT DIFFERENCES BETWEEN DIRECT AND REVERSE GRINDING CIRCUITS?

The mining industry is famous for many paradigms regarding different flowsheet designs and the use of new technologies and equipment. In this context, a question often performed to process engineers is: what grinding circuit is more efficient, the direct or the reverse? A precise answer could only be given by experimental data and simulations. Simulations were performed using ModSimTM software considering parameters obtained by batch mill tests of an iron ore sample. The simulations, preliminarily, indicated no significant differences between the two circuit configurations for the sample tested. Subsequently, tests were conducted on a pilot scale with detailed measurement of all the variables necessary for a correct interpretation of the differences between the direct and reverse circuits. The test results confirmed the prediction obtained by simulation. This work provides the basis to test other ores and to understanding better the real differences between grinding circuit configurations. Thus, it is expected that some myths of the mineral industry, with respect to flowsheet choices, are overcome

Vertimill™ pilot scale tests simulated by perfect mixing model

Minas-Rio Project, Anglo American property, located in Brazil, considers Vertimill™ to make the particle size distribution adequate to feed slurry pipeline. A pilot test campaign was carried out at Metso's pilot plant facility located in York city, Pennsylvania State, USA, to provide information to scale up the industrial grinding circuit. The perfect mixing model, normally used to simulate ball mills, was used to compare the direct and reverse circuit configurations. The simulations were based on the appearance function determined from the laboratory tests using a batch tube mill. The combined breakage rate/discharge rate function (r/d) was determined from Vertimill™ feed and product particle size distributions obtained from pilot tests. The residence time was estimated considering the mill hold-up and solids flow rate. The simulation results show that there are no significant differences between direct and reverse circuits for the sample tested

PARÂMETROS CINÉTICOS DE MOAGEM DE ITABIRITOS COMPACTO E FRIÁVEL

Duas amostras de minério de ferro classificadas como itabiritos compacto e friável foram testadas com relação a moabilidade. Os testes foram realizados em um moinho de bolas em escala de laboratório com torquímetro para medição precisa da potência. Os parâmetros cinéticos das amostras foram determinados através do aplicativo Moly-Cop Tools 2.0. Simulações foram realizadas com o mesmo aplicativo para previsão do comportamento do circuito de moagem com cada uma das amostras estudadas. Os resultados indicam que a amostra de itabirito friável possui maior consumo específico de energia, mesmo sendo uma amostra de granulometria mais fina que a amostra de itabirito compacto

Vertical mill simulation applied to iron ores

The application of vertical mills in regrind circuits is consolidated. This type of mill is now attracting interest in primary grinding applications, due to its higher efficiency when compared to ball mills, which are usually used at this stage. In this study, a coarse sample of iron ore was tested in a pilot scale grinding circuit with a vertical mill. Other three samples of pellet feed had already been tested with the methodology used in this study. The sample of coarse iron ore was characterized in laboratory tests carried out in a small batch ball mill. Selection and breakage function parameters were determined from the laboratory tests. The parameters were then used for simulating the pilot scale tests using Modsim™ software. The model previously implemented in Modsim™ has been successfully applied to represent the vertical mill operated with different ores. The simulations produced particle size distributions that were very close to the actual size distributions, and the predictions were accomplished only by imputing the calibrated parameters from the batch tests, the power draw and the feed size distribution of the pilot tests. The methodology is therefore useful for scale-up and simulation of vertical mills, only requiring laboratory tests that can be carried out in standard laboratory batch ball mills with small amounts of samples

PREVISÃO DE DISTRIBUIÇÃO GRANULOMÉTRICA DE PRODUTO DE MOINHO VERTIMILL

Uma campanha de testes em escala piloto com um moinho VertiMill foi realizada com amostras de minério de ferro e de minério de cobre da Vale S.A com o objetivo de avaliar a aplicação deste tipo de equipamento em moagens primárias. Os profissionais envolvidos no dimensionamento de novos circuito de moagem tem discutido bastante sobre qual metodologia utilizar para dimensionar os moinhos VertiMill. Este trabalho apresentada uma nova metodologia para escalonamento e simulação de moinho VertiMill através do modelo do balanço populacional utilizando parâmetros de quebra determinados através de um moinho de bolas tubular em escala de laboratório. O teste requer pequenas quantidades de amostras e pode ser realizado em qualquer laboratório de processo que possua um moinho de bolas para testes. Para a determinação dos parâmetros de quebra foi utilizado um software específico denominado BatchMillTM, que interpola as várias curvas granulométricas geradas nos testes de bancada de forma a obter parâmetros de quebra que representem uma ampla faixa de operação do moinho VertiMill. Estes parâmetros de quebra foram utilizados para simulação dos testes em escala piloto utilizando o software ModsimTM, que simula a operação de equipamentos de moagem e classificação. Os resultados obtidos nas simulações indicam que é possível prever a distribuição granulométrica do produto do moinho VertMill com precisão aceitável utilizando a metodologia proposta

Scale up and simulation of Vertimill™ pilot test operated with copper ore

Vertimill™ has been used in regrind circuits during the past years due to its greater efficiency when compared to the conventional tube ball mill. This paper presents the Vertimill™ pilot grinding tests with a sample of copper ore carried out in closed circuit with a high frequency screen. The sample was crushed 100% to <6 mm. All operating variables were measured under controlled conditions to produce a mass balance of the test. A laboratory batch ball mill was used to characterize the sample in order to determine the energy specific selection function and the breakage function. Previous studies have shown that the Vertimill™ produces larger values of the selection function and a constant scaling factor can be used to simulate the product particle size distribution of the Vertimill™ from the batch ball mill grinding tests. The results of the simulations showed that it is possible to estimate the product particle size distribution of the Vertimill™ pilot scale from breakage parameters determined from a lab-scale batch ball mill. These results confirm that the Vertimill™ and the conventional ball mill use similar mechanisms of impact and that the main difference between them is the intensity and frequency of the impacts

A Case Study of Incorporating Variable Recovery and Specific Energy in Long-Term Open Pit Mining

Integrated Optimization can find optimized solutions for a project to define open pit and mine scheduling with greater reliability. This work aims to demonstrate how the insertion of geometallurgical variables can significantly change the financial return of a project. Two geometallurgical variables are considered in mine planning simulations. Specific energy corresponds to the energy consumed in the comminution of the ore, and process recovery measures the percentage of metal incorporated into the product. Three scenarios were developed considering an iron ore deposit. In the Base Case (BC) scenario, the recovery was fixed, and the specific energy of comminution was not considered. GeoMet1 considers the variable recovery varying for each block. GeoMet2 considered both recovery and specific energy as variables varying for each block. GeoMet1 and GeoMet2 presented Net Present Value (NPV), respectively, as 3.68% and 13.57% lower than the BC. This overestimation of the BC results can be viewed as an optimistic case of mine planning that is very common in the mining industry. These results show that the use of specific energy and recovery variables is fundamental to obtaining more reliable mine planning