Abstract:(Concentração de finos de bauxita por concentração densitária) ResumoA CBA (Companhia Brasileira de Alumínio) tem uma usina de beneficiamento em Itamarati de Minas, MG. Essa usina trata dois tipos de bauxita diferentes, um originado da laterização de gnaisses e outro de anfibolitos. Ambos os minérios têm o mesmo comportamento nas frações granulométricas grosseiras, mas tornam-se diferentes abaixo de 0,355 mm (42 # Tyler). Nesses tamanhos menores, os minérios gnáissicos são ricos em quartzo e os anfibolíticos s… Show more
“…The scrubbing action could also decrease the silica and iron content to 9.37 and 19.7 % respectively in the coarser fraction of the product. It is also possible to remove around 31 % of silica from the bulk ore. Chaves et al [15] carried out scrubbing of the feed in drum scrubbers, desliming in cyclones, and screening of the scrubbed bauxite in high frequency screens (0.355 mm)-the ?0.355 mm product is an usable final concentrate.…”
A low grade bauxite sample of central India was thoroughly characterized with the help of stereomicroscope, reflected light microscope and electron microscope using QEMSCAN. A few hand picked samples were collected from different places of the mine and were subjected to geochemical characterization studies. The geochemical studies indicated that most of the samples contain high silica and low alumina, except a few which are high grade. Mineralogically the samples consist of bauxite (gibbsite and boehmite), ferruginous mineral phases (goethite and hematite), clay and silicate (quartz), and titanium bearing minerals like rutile and ilmenite. Majority of the gibbsite, boehmite and gibbsitic oolites contain clay, quartz and iron and titanium mineral phases within the sample as inclusions. The sample on an average contains 39.1 % Al 2 O 3 and 12.3 % SiO 2 , and 20.08 % of Fe 2 O 3 . Beneficiation techniques like size classification, sorting, scrubbing, hydrocyclone and magnetic separation were employed to reduce the silica content suitable for Bayer process. The studies indicated that, 50 % by weight with 41 % Al 2 O 3 containing less than 5 % SiO 2 could be achieved. The finer sized sample after physical beneficiation still contains high silica due to complex mineralogical associations.
“…The scrubbing action could also decrease the silica and iron content to 9.37 and 19.7 % respectively in the coarser fraction of the product. It is also possible to remove around 31 % of silica from the bulk ore. Chaves et al [15] carried out scrubbing of the feed in drum scrubbers, desliming in cyclones, and screening of the scrubbed bauxite in high frequency screens (0.355 mm)-the ?0.355 mm product is an usable final concentrate.…”
A low grade bauxite sample of central India was thoroughly characterized with the help of stereomicroscope, reflected light microscope and electron microscope using QEMSCAN. A few hand picked samples were collected from different places of the mine and were subjected to geochemical characterization studies. The geochemical studies indicated that most of the samples contain high silica and low alumina, except a few which are high grade. Mineralogically the samples consist of bauxite (gibbsite and boehmite), ferruginous mineral phases (goethite and hematite), clay and silicate (quartz), and titanium bearing minerals like rutile and ilmenite. Majority of the gibbsite, boehmite and gibbsitic oolites contain clay, quartz and iron and titanium mineral phases within the sample as inclusions. The sample on an average contains 39.1 % Al 2 O 3 and 12.3 % SiO 2 , and 20.08 % of Fe 2 O 3 . Beneficiation techniques like size classification, sorting, scrubbing, hydrocyclone and magnetic separation were employed to reduce the silica content suitable for Bayer process. The studies indicated that, 50 % by weight with 41 % Al 2 O 3 containing less than 5 % SiO 2 could be achieved. The finer sized sample after physical beneficiation still contains high silica due to complex mineralogical associations.
“…Tailings dams have been the preferred method of disposal of such materials [3]. However, recent dam breach events in Brazil [4] and the growing demand for mineral goods [5] have enhanced the appeal of alternative tailings disposal methods and a more effective recovery of minerals contained in such tailings [3,[6][7][8][9][10][11][12][13][14][15]. For both economic and socioenvironmental reasons, the mining industry has sought to identify these materials' applicability by recovering more products in mineral processing plants.…”
The mining industry has seen a significant decline in mill feed grade in recent years, resulting in an ongoing build-up of materials not recovered at the mineral processing plants whose economic value has not yet been determined. Tailings dams have been the preferred method of disposal of such materials. However, recent dam breach events and the growing demand for mineral goods have enhanced the appeal of a more effective use of mined materials to prevent tailings accumulation and reduce social and environmental impacts, in line with the environmental, social and governance (ESG) principles that most companies have adopted. Different techniques can be used to recover economically valuable minerals contained in such materials, among which magnetic separation stands out for reasons of cost, production capacity, and recent developments of new equipment and matrices for wet high-intensity magnetic separators. The outcome includes gains in capacity, grade, and recovery yield. This paper assessed the use of a matrix developed by the company Gaustec, called BigFlux, in the magnetic separation of depressed product from the flotation process at Nexa Resources's Vazante mine. Laboratory-scale magnetic separation tests were conducted using standard and an optimized matrix. For a 59% iron concentrate, the metallurgical recovery using such optimized matrix reached 72.6%, up 4% from the figure resulting from the use of the standard matrix, thus indicating that the use of the optimized matrix can improve the magnetite recovery process of the studied material.
“…It is a common industrial practice to introduce project modifications in order to improve the operation product in terms of mass recovery or content of interesting elements in bauxite plants [6,9,10]. In Bergerman and Chaves' works [9], for instance, the modifications were the installation of spiral concentrators in the bauxite processing plant of the Itamarati de Minas plant with the aim of recovering the profitable fine fraction material that had been discharged.…”
In the Miraí processing plant (Votorantim Metais), bauxite is processed with an average feed of 1,000 t/h in a circuit with crushing, scrubbing and screening stages. Two plant unit operations needed optimization: (1) The scrubber promoted not only the attrition and disaggregation of bauxite, but was also its griding; (2) The screened fine products had material with significant amounts of available aluminium (AA) and low reactive silica (RS) contents. In this work, modifications were introduced in the scrubber and screening circuit in order to improve the plant performance. A pulp lifter was installed in the scrubber. In addition, the apertures of the primary and secondary screens were changed. Statistical univariate analysis was used to support the process gain due to the introduced modifications. According to the variance analysis (ANOVA), there was no loss of product quality since the resulting AA, RS and iron (Fe) contents agree with the metallurgical specification and the previous results before the optimization work. The mass recovery increased by 3.88%, which means a gain of 43 t/h for the operation. Keywords: Bauxite; Scrubbing; Screening; Statistical analysis.
AVALIAÇÃO ESTATÍSTICA DA OTIMIZAÇÃO DAS OPERAÇÕES DE ATRIÇÃO E PENEIRAMENTO NO BENEFICIAMENTO DE BAUXITA ResumoNa planta de beneficiamento de Miraí (Votorantim Metais), bauxita é processada com uma alimentação média de 1.000 t/h em um circuito composto por britagem, desagregação em um scrubber e peneiramento. Duas operações da planta necessitavam otimização: (1) O scrubber promovia não só a atrição da bauxita como também sua fragmentação; (2) O peneiramento descartava material com quantidade significativa de alumínio aproveitável (AA) e baixo teor de sílica reativa (SR). Neste trabalho mudanças foram introduzidas no scrubber e no circuito de peneiramento para aprimorar o desempenho da planta. Um sistema de descarregamento foi instalado no scrubber. Além disso, a abertura das peneiras primárias e secundárias foi modificada. Análises estatísticas univariadas foram usadas para confirmar o ganho do processo devido às modificações introduzidas. De acordo com a análise de variância (ANOVA), a qualidade do produto não piorou, pois os teores de AA, SR e ferro (Fe) estão de acordo com a especificação metalúrgica. A recuperação mássica aumentou em 3,88%, o que significa um ganho de 43 t/h para a operação.
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