Mauricio Bergerman | Universidade de São Paulo (original) (raw)

Papers by Mauricio Bergerman

Minerals Engineering, 2023

Grinding ores in conventional ball mills demands high energy consumption, resulting in relatively... more Grinding ores in conventional ball mills demands high energy consumption, resulting in relatively high operating costs in a typical mineral processing industrial plant. Whether in the initial stages of a mining project or during its operation, conducting tests to determine the processing circuit’s energy consumption throughout the life of mine is necessary in order to reduce such high operating costs. Traditional tests used to determine the energy consumption in grinding, like the Bond Ball Mill test, are relatively time-consuming and require significant amounts of sample, e.g., 8–10 kg, which is not always available in the initial stages of a mineral project or geometallurgical studies. Several authors have developed simplified tests to predict ball mill’s energy consumption, typically using the Bond Ball Mill Work Index (BBMWI) as a reference. One option requiring less mass is the Hardgrove mill, traditionally used in the laboratory to determine the energy required to grind coal in roller mills. This test requires 50 g of sample, and the result is based on the amount of fines at the end of grinding to a fixed time. The present study used a modified Hardgrove test to predict the BBMWI. This test involves the measurement of the torque, uses a fixed sample volume with different particle feed sizes from the Hardgrove standard, and determines the specific energy related to the percentage of product passing through the closing size screen of the Bond test, defined as the size specific energy. The results indicated that for a set of 13 samples with the 150 µm closing screen, the average error associated with the predicted BBMWI is within ±2.3%. Further results indicate an error of ±3.1% for 20 samples with the 106 µm closing screen. The correlations presented here are proposed to be validated and/or adjusted for different ores and mines. The proposed test is thus suitable for geometallurgical studies and other applications where relatively small samples are available. In addition, this is a low-cost test, has a quick turn-around time, it is simple to conduct and does not require the handling of heavy loads by operators.

Contribuição técnica para o Physical Separation'17, 2017

Pre-concentration consists of the preliminary discarding of a fraction of the mineral processing ... more Pre-concentration consists of the preliminary discarding of a fraction of the mineral processing plant feed which contains little or none of the mineral of interest, reducing the mass to be processed in downstream operations (e.g. milling, concentration, and dewatering) as well as the capital and operational costs. In this context, this study investigates the performance of density and sensor separation techniques in the removal of the carbonatic gangue of a Brazilian zinc ore in size fractions typical of crusher products, using sink and float tests with heavy liquid media, jig stratification, and laboratory-scale ore-sorting tests using an x-ray transmission (XRT) sensor. The best results were obtained in the sink and float in heavy liquid and indicate the possibility of discarding 30% of the feed mass of the plant, removing over 50% of the carbonate while losing only 2% of the zinc. The ore sorting tests also presented positive results, with an average metallurgical recovery of 93% in 73% of the mass. The results indicate a significant potential reduction of Capex and Opex using these pre-concentration methods.

Contribuição técnica para o 24th World Mining, 2016

The pre-concentration consists on the previous discard of a fraction of the mineral processing pl... more The pre-concentration consists on the previous discard of a fraction of the mineral processing plant feed with few or none quantity of the mineral of interest, reducing the mass to be processed in the downstream operations, as well the capital and operational costs. In this context, this study aims to verify the susceptibility of the silicate zinc ore from Votorantim Metais, Vazante/MG (Brazil), for pre-concentration by density and magnetic methods. For this purpose, tests have been developed in a magnetic roll separator operating under high field (10,000 gauss) and also on sink/float in dense liquids varying between 2.75 to 2.95 g/cm³ and in coarse particle size: + 6,35, - 6,35 + 3,35 e -3,35 + 1,18 mm. The former results show the possibility to discard more than 50% of the plant mass and zinc metallurgical recoveries above 90%. It also shows that the discard of contaminants, as MgO, can achieve 80%. The results for the magnetic separation have not been meaningful in comparison with the density separation.

The pre-concentration consists on the previous discard of a fraction of the mineral processing pl... more The pre-concentration consists on the previous discard of a fraction of the mineral processing plant feed with few or none quantity of the mineral of interest, reducing the mass to be processed in the downstream operations, as well the capital and operational costs. In this context, this study aims to verify the susceptibility of the silicate zinc ore from Votorantim Metais, Vazante/MG (Brazil), for pre-concentration by density and magnetic methods. For this purpose, tests have been developed in a magnetic roll separator operating under high field (10,000 gauss) and also on sink/float in dense liquids varying between 2.75 to 2.95 g/cm³ and in coarse particle size: + 6,35,-6,35 + 3,35 e-3,35 + 1,18 mm. The former results show the possibility to discard more than 50% of the plant mass and zinc metallurgical recoveries above 90%. It also shows that the discard of contaminants, as MgO, can achieve 80%. The results for the magnetic separation have not been meaningful in comparison with the density separation.

Constantly the moisture is a problematic control point to the mining industry, because it can gen... more Constantly the moisture is a problematic control point to the mining industry, because it can generate several disorders as the handling, loading and unloading of ore, transportation and even at the metallurgical process. Therefore it is necessary to use drying methods that can varies from natural drying until industrial equipment systems. The Poços de Caldas unit of Votorantim Metais has approximately 27% moisture content on its shipped bauxite, which implies a high surcharge on freight and with the steam used for drying the bauxite before the metallurgical process. To solve the problem of ore drying, different methods were studied and analyzed, among which the methods of natural drying, fines washing, drying systems with hot gas generator, fluidized bed dryer and dryer hammer crusher. Analyzing the economic viability for each method against the reality of the Bauxite Production Unit from CBA at Poços de Caldas, the selected method for further studies were the 371

Sossego mill was Vale’s first plant to operate a semi-autogenous mill for processing copper and g... more Sossego mill was Vale’s first plant to operate a semi-autogenous mill for processing copper and gold sulfide ore. The mill is located in Brazil. After the circuit commissioning, it was found out that certain variables were contributing to a lower than expected hourly output. A number of optimization and upgrading measures were taken over the 10 years of operation of the semi-autogenous mill, including changes in the grate area, size and arrangement of aperture, liner profile and rock blasting plan. This work describes the main aspects of the circuit design and the improvements introduced over the first years of operation.

A pilot scale test program was conducted to evaluate the size reduction performance of HPGR (High... more A pilot scale test program was conducted to evaluate the size reduction performance of HPGR (High Pressure Grinding Rolls) operating in different circuit configurations. For this purpose a series of pilot-HPGR locked cycle tests were performed with medium and high pressures to simulate the HPGR operation in closed circuit with a screen, with partial product recycle, and with edge recycle. Logged instrumentation data such as roller speed, working gap, operating pressure, and power draw were used in combination with material test results such as particle size distributions, flake density, flake thickness, and bulk density of the feed for calculation of HPGR operational parameters. The paper reports the results from the pilot HPGR test work. The analysis reported herein includes an evaluation and comparison of different circuit configurations of the HPGR operation in terms of energy consumption, capacity and product fineness and also discusses the benefits of various circuit arrangements.

The refractory bauxite needs to present less than 2.5% of Fe 2 O 3 to be applied in the ceramics ... more The refractory bauxite needs to present less than 2.5% of Fe 2 O 3 to be applied in the ceramics industry. The depletion of high Al 2 O 3 grade deposits has stimulated the improvement of bauxite concentration methods in order to remove iron-bearing minerals. The objective of this study was to evaluate the influence of collector dosage, pH and milling time on the gibbsite flotation performance. Firstly, the sample mineralogical composition was determined by means of X-ray diffraction (XRD) and binocular loupe analysis. X-ray fluorescence (XRF) analysis was used to determine the sample chemical composition. Flotation was then accomplished by using hydroxamate as gibbsite collector, sodium silicate as silicate depressant and starch as iron-bearing minerals depressant. The bauxite Fe 2 O 3 content was reduced from 7.66% to 4.81-5.03%. In addition, the flotation performance decreased by diminishing the pH from 9.5 to 8.5 or increasing the pH to 10.5. The milling time influence on the flotation indicates that the presence of slime can significantly affect the gibbsite concentration.

A usina do Sossego foi a primeira operação da Vale S.A. a operar com um moinho semi-autógeno (SAG... more A usina do Sossego foi a primeira operação da Vale S.A. a operar com um moinho semi-autógeno (SAG) para o processamento de minério sulfetado de cobre e ouro. A usina está localizada no sudeste do estado do Pará. O circuito de cominuição foi projetado para processar 41.000 toneladas por dia de run of mine, sendo o circuito composto por um britador primário, um moinho semi-autógeno de 11,6 m de diâmetro que opera em circuito fechado com britadores cônicos, seguido de dois moinhos de bolas de 6,7 m de diâmetro. O projeto do circuito se baseou em dados de extensa campanha piloto, assim como em simulações baseadas nos resultados de ensaios de caracterização em amostras de furos de sonda. Após o comissionamento do circuito, observou-se que algumas variáveis estavam contribuindo para vazões horárias abaixo das esperadas. Uma série de otimizações e adequações foram realizadas ao longo dos 10 anos de operação do moinho semi-autógeno, incluindo mudança na área aberta, tamanho e disposição das aberturas das grelhas, perfil dos revestimentos e mudanças no plano de fogo da mina. Este trabalho descreve os principais aspectos do projeto do circuito, assim como as otimizações realizadas ao longo dos primeiros anos de operação.

A usina do Sossego processa um minério sulfetado de cobre e ouro. A etapa de flotação compreende ... more A usina do Sossego processa um minério sulfetado de cobre e ouro. A etapa de flotação compreende estágios rougher, cleaner e scavenger do cleaner, sendo que os concentrados das etapas rougher e scavenger do cleaner passam por um estágio de remoagem antes de seguir para a etapa cleaner. Ao longo dos primeiros anos de operação da usina, observou-se que a granulometria de alimentação da remoagem estava consistentemente mais fina que o esperado, mesmo considerando-se que a granulometria de alimentação da flotação (etapa rougher) estava dentro dos parâmetros esperados e significativamente mais grossa que o concentrado rougher. Este trabalho apresenta os resultados das amostragens de campo para identificar a origem de tal diferença e quantificar a mesma, assim como ilustra os impactos de tal diferença na etapa de remoagem do concentrado.

Feldspato é um termo aplicado a um grupo de aluminosilicatos combinados com proporções variáveis ... more Feldspato é um termo aplicado a um grupo de aluminosilicatos combinados com proporções variáveis de potássio, sódio, cálcio entre outros cátions. Na indústria de cerâmica, em específico na fabricação de porcelanato de elevada brancura, o teor de óxido de ferro (Fe2O3)deve ser inferior a 1%. Neste contexto, o presente trabalho teve como objetivo reduzir o conteúdo de Fe2O3 do minério rico em feldspato (foiaíto), do maciço de Poços de Caldas por meio da técnica de flotação reversa, para atender às especificações exigidas pela indústria de cerâmica. Inicialmente a amostra de minério foi preparada com relação a sua granulometria por meio de processos de britagem, moagem e deslamagem. Em seguida, a amostra foi caracterizada por análise de Fluorescência de Raios-X (FRX) e Difração de Raios-X (DRX). O desempenho de diferentes tipos de coletores aniônicos (ácido graxo, sulfonato, sulfato e hidroxamato) de minerais portadores de ferro em diversas dosagens (200, 400 e 600 g/t) foi avaliado em um estágio de flotação rougher. De acordo com os resultados dos ensaios de concentração, o reagente que apresentou o maior desempenho foi o sulfato MDB908 na dosagem de 600 g/t. A redução de Fe2O3 nesta condição foi de 3,1% para 1,9%. Os resultados indicaram que o teor desejado de Fe2O3 pode ser alcançado com o aumento da dosagem do reagente selecionado e a introdução de etapas de limpeza.

Energy efficiency is extremely important in secondary grinding (regrinding) as specific consumpti... more Energy efficiency is extremely important in secondary grinding (regrinding) as specific consumption are greater than obtained in primary grinding. Moreover, finer grinding sizes are a trend in new grinding circuits therefore increasing the energy consumption, as well as respective capital and operating costs. In Brazil regrinding sizes between 40 a 20 m are common in greenfield projects. As horizontal ball mills show decreasing efficiency as grinding sizes are finer than 50 m, this work shows regrinding equipment alternatives to ball mills focusing on vertical mills. A number of survey campaigns were carried out on four industrial operations in which vertical mills were installed in the respective regrind circuit. A new batch test was developed and
validated to predict the energy consumption and product size distribution associated to vertical mills.

Minerals Engineering, 2023

Contribuição técnica para o Physical Separation'17, 2017

Contribuição técnica para o 24th World Mining, 2016

The pre-concentration consists on the previous discard of a fraction of the mineral processing pl... more The pre-concentration consists on the previous discard of a fraction of the mineral processing plant feed with few or none quantity of the mineral of interest, reducing the mass to be processed in the downstream operations, as well the capital and operational costs. In this context, this study aims to verify the susceptibility of the silicate zinc ore from Votorantim Metais, Vazante/MG (Brazil), for pre-concentration by density and magnetic methods. For this purpose, tests have been developed in a magnetic roll separator operating under high field (10,000 gauss) and also on sink/float in dense liquids varying between 2.75 to 2.95 g/cm³ and in coarse particle size: + 6,35,-6,35 + 3,35 e-3,35 + 1,18 mm. The former results show the possibility to discard more than 50% of the plant mass and zinc metallurgical recoveries above 90%. It also shows that the discard of contaminants, as MgO, can achieve 80%. The results for the magnetic separation have not been meaningful in comparison with the density separation.

The practice of computer simulation is traditionally used for the optimization of industrial grin... more The practice of computer simulation is traditionally used for the optimization of industrial grinding circuits. The methodology usually includes surveying campaigns at the selected circuit, followed by data analysis, mass balancing and modeling. The latter consists in fitting mathematical models of each process equipment. Once the simulator is calibrated, a number of simulations may be carried out in order to explore different operating scenarios, related to optimization on the basis of selected performance indices. The simulation is thus an alternative for extensive and expensive pilot plant campaigns, as well as industrial tests. Accordingly, simulation is a low cost and low time demanding alternative, allowing the detailed assessment of several flowsheet options and/or operation conditions, even though it demands a qualified person and a professional software.
This work presents an application of computer simulation program carried out at the Vale´s Sossego industrial grinding plant, located at the south-east part of Para state. As the Sossego circuit includes the first large diameter semiautogenous mill installed in Brazil, the literature review was largely focused on operating and optimization aspects of such a process, thus seeking to consolidate this kind of knowledge in Brazil.

Prezados Colegas, Em nome da Universidade Federal de Alfenas agradecemos a todos pela participaçã... more Prezados Colegas,
Em nome da Universidade Federal de Alfenas agradecemos a todos pela participação no 1º Workshop de Educação em Engenharia de Minas. Este evento surgiu do desejo e da necessidade de discutir a educação em engenharia no âmbito do curso de Engenharia de Minas. Há eventos tradicionais de Educação em Engenharia, como por exemplo o COBENGE (Congresso Brasileiro de Educação em Engenharia), porém nada específico para a área de Mineração. Temos um universo onde existem atualmente 26 cursos de graduação em Engenharia de Minas, em um total de 2.386 vagas autorizadas por ano, 18 Cursos Técnicos em áreas afins de Mineração, totalizando 890 vagas/ano e 6 cursos
de mestrado acadêmico em Engenharia de Minas, perfazendo 182 alunos em 2015. Desses programas, apenas 2 têm também programa de doutorado na área e outros 2 são cadastrados como programas de mestrado profissional. Há vários outros programas de pós-graduação no território nacional que apresentam a palavra “mineração”, ou suas
variantes, mas não são cadastrados na Capes como programas da área de Engenharia de Minas. Assim, há muito o que discutir: projetos político-pedagógicos, conteúdo e duração dos cursos, dinâmica curricular, métodos de ensino, inserção de novas ferramentas de aprendizagem, atribuições profissionais, perfil do egresso, mercado de
trabalho, extensão universitária, panorama de pós-graduação, possibilidades de formação fora do país... Daí veio a escolha do subtítulo do evento “ Rumos da Engenharia de Minas no Brasil”. Assim, com a inspiração e sugestões dadas gentilmente pelo Prof. Carlos Alberto Pereira, este primeiro evento foi idealizado, de modo a iniciar
as discussões na área, para traçarmos um perfil geral do setor, pensarmos em planos de ação para a melhoria das atividades em todos os cursos e fomentarmos a realização de outros eventos. Agradecemos à Comissão Organizadora do XVI ENTMME, pelo apoio na
realização deste evento, aos palestrantes e aos participantes, na certeza de que as discussões trarão informações muito importantes a todos os cursos e envolvidos. Não podemos parar por aqui. Que esse tenha sido o primeiro evento de muitos!
Carolina Del Roveri
Coordenação Geral do 1º Workshop de Educação em Engenharia de Minas