Abstract The Brazilian ferroalloy industry faces a highly competitive scenario in the foreign market. Among the key factors to determine the price of its products, electric energy stands out as one of the main inputs. So, the possibility of energy being unavailable or having high prices causes a direct impact in the ferroalloy chain. On the other hand, the renewable energy market, especially the solar photovoltaic (SPV) energy shows extensive growth due to technological advances and recent regulation. Connecting both contexts, this study investigates a way to apply the great moment of the SPV energy sector to the ferroalloys industry. Firstly, the ferroalloy sector data was searched in order to develop a model of ferroalloy production by using the average data of production and electric energy consumption, called model-ferroalloy. So an SPV power plant was estimated to supply its electric energy demand. It was considered in four different scenarios according to current law and its economic viability verified. From these studies, the viability of implementing solar photovoltaic energy to ferroalloys industry was determined. The levelized cost of energy (LCOE) comparative shows that SPV energy has a lower price than conventional sources, no matter if it is in the free or regulated energy market. Furthermore, the necessary investment, according to the results found, has good attractiveness in the financial market point of view.

The mineralogical characterization studies search for the best processing route, with the lowest environmental impact, aiming to improve the use of mineral resources. The electronic quantitative mineralogy (EQM) provides quickly and accurately great information about the characteristics of these materials. This work aims to characterize iron ore tailings by EQM as the main tool. It has selected seven samples of itabirite ores flotation tailings from the main mining regions of the Quadrilatero Ferrifero, Brazil. All samples were mostly composed by quartz and iron minerals, with a low presence of mixture particles of these minerals - less than 20% of the sample mass. Due to the difference between the size of particles of quartz and iron minerals, it has observed an opportunity to reprocess the fractions -37µm + 5µm of the studied tailings, with a potential recovery of 12% of the total sample mass generated for AM4, AM6 and AM7 and more than 5% for samples AM1, AM2, AM3 and AM5.

A maior participação de minérios contendo uma maior quantidade de sílica de diferentes origens no beneficiamento e, por sua vez, no processo de sinterização é uma tendência natural, conseqüência da mudança no perfil do run-of-mine. No sinter, a sílica tem o papel importante de garantir um volume adequado de escória e propiciar uma resistência mecânica satisfatória para as operações de manuseio, transporte e para seu uso nos altos-fornos. Nesse contexto, o objetivo desse trabalho foi caracterizar uma fonte de sílica (itabirito compacto) avaliando sua influência nas frações nucleantes, intermediárias e aderentes de um sinter feed hematítico anidro sobre as propriedades físicas e metalúrgicas do sínter produzido em escala-piloto, além da produtividade e do consumo de combustível na sinterização piloto.

In the hematite/itabirite relationship the silica proportion is increasing, changing the run-of-mine profile. Although process routes are being adequated because of this change, this is occurring without the profound knowledge required with regard to the quality impact of the silica in the sinter feed within the sintering process parameters and the physical and metallurgical quality of the sinter product. The objective of this study is to characterize a hematite sinter feed containing silica (compact itabirite) with the following grain size distribution: adherent, intermediate and nucleant, evaluating the influence of this source of silica in the sinter characteristics and in the sintering process.

Crushing residues of FeSiMn and high-carbon (HC) FeMn alloys were characterized in order to evaluate their recycling possibility. Particle size determination was performed by screening, followed by chemical analysis of each particle size range using plasma spectrometry (ICP-AES). The slag content was identified and quantified by optical microscopy. All of the fines with grain sizes above 1.18 mm presented alloy contents in excess of 99 wt. (%) and were determined to need no further concentration prior to recycling. However the contents of Mn, Fe, Si and P in the fraction below 1.18 mm did not meet the chemical specifications for commercial manganese alloys, except for phosphorous. Optical microscopy of the fraction below 1.18 mm, showed that 87.95% of the FeSiMn corresponded to the alloy and that the slag content was 12.05%. For the HC-FeMn sample, 95.07% corresponded to the alloy and only 4.93% to the slag. These results revealed potential for gravity concentration and recycling, reducing the residues in about 95% and improving the process productivity.

Alguns dados sobre a injeção de carvão pulverizado são mostrados bem como uma descrição do modelo de combustão de partículas com elevado gradiente térmico construído na Escola de Minas - UFOP. Usando misturas de três carvões, bem como pré-aquecimento de carvão, foi possível constatar que: o uso de misturas de mais de dois carvões bem como o seu pré-aquecimento podem ser duas técnicas a serem usadas em altos-fornos no sentido de melhorar ainda mais os rendimentos obtidos nos reatores que usam a técnica de injeção.

Some data about coal powder injection have been shown and one physical model, with high thermal gradient constructed at Escola de Minas-UFOP is described Using mixture of coal (3) and pre-heating of the coal some tests have been done, giving the conclusions below: pre heating of coal could be a good idea for improving the results obtained into the blast furnace, so mixture of more than two coals, not common practiced, could improve the combustion rate.

Esse artigo apresenta uma análise crítica da metodologia empregada para avaliação técnica rotineira de finos de minérios de ferro para sinterização, tanto por parte das siderúrgicas, quanto pelas minerações brasileiras, com base apenas no controle granulométrico e químico. Sugere-se a realização da caracterização mineralógica das partículas nucleantes, intermediárias e aderentes do sinter feed, visando à otimização do processo e à melhoria da qualidade intrínseca do produto, destacando os principais atributos que devem constituir a sua identidade microestrutural. Vislumbra-se, para os próximos anos, uma verdadeira revolução nos critérios que norteiam a análise técnica de minérios para os processos industriais de aglomeração.

This paper provides a critical analysis of the methodology used in Brazil for routine technical evaluation of iron ore fines used in the sintering process based uniquely on chemical and granulometric parameters. The mineralogical characterization of adherents, intermediates and nucleantes particles of sinter feed and the main attributes that should constitute its microstrutural identity have been highlighted. It should contribute a great deal to optimize the process parameters during the various stages of the sintering process as well as promote better intrinsic sinter quality. Based on these concepts, it is expected that in future years, significant criterias will be developed for technical analysis of iron ores fines used in agglomeration industry.