Proposta de recupera����o de granalha n��o ativa no desdobramento de rochas ornamentais em teares multil��minas

No processo de desdobramento dos blocos de granito e basalto, os teares utilizam granalha de ferro/a��o como abrasivo gerando grandes quantidades de material fino a base dos minerais constituintes das rochas, da granalha cominu��da e do desgaste das l��minas (lama abrasiva). Este trabalho tem por objetivo caracterizar a lama abrasiva no est��gio em que esta sai do processo de desdobramento das rochas (rejeito). Isto acontece quando a granalha atinge a fra����o < 0,42 mm e perde suas propriedades abrasivas, dispensando, desta forma, sua presen��a no sistema. O equipamento utilizado para a retirada da lama n��o abrasiva �� o hidrociclone, que atrav��s do overflow conduz o rejeito a uma bacia de decanta����o. A caracteriza����o do rejeito foi realizada tanto em amostras individuais, como em amostras coletadas diretamente nos tanques de decanta����o provenientes da serragem de diferentes tipos litol��gicos, enfatizando, principalmente, os aspectos f��sicos (morfol��gico e granulom��trico) que caracterizam esta lama n��o abrasiva. Este estudo busca, tamb��m, quantificar o volume produzido de rejeito pelas principais empresas de desdobramento do setor, bem como o prov��vel aproveitamento econ��mico, atrav��s de m��todos de separa����o mineral apropriados, de modo que se determine uma rota vi��vel na ordem t��cnica e econ��mica. Outro aspecto abordado foi o impacto ambiental gerado pela deposi����o destes rejeitos, uma vez que, poucas empresas do setor t��m a preocupa����o efetiva de adequar suas bacias de decanta����o com as normas vigentes da legisla����o ambiental. Ap��s o esgotamento dessas bacias, os rejeitos s��o descartados em aterros pr��ximos ��s empresas ou nos ���lix��es��� e aterros das prefeituras municipais. Observa-se, desta forma, que n��o h�� o devido tratamento, haja vista, o material apresentar elevado percentual de s��lidos (ferro, quartzo, feldspato) e pH em torno de 12 (alcalino).

Estudo de misturas de areia-asfalto e cinza-cal para emprego em pavimentos urbanos

A execu����o da pavimenta����o da malha vi��ria municipal urbana deve seguir um eficiente planejamento t��cnico-econ��mico para adequada gest��o de recursos financeiros. Solu����es alternativas como: bases de solo estabilizado com cinza-cal ou areia-asfalto, e revestimentos de areia-asfalto, reafirmam-se de grande valia para pavimentos de baixo custo na regi��o litor��nea do Rio Grande do sul, onde h�� abund��ncia de areias e falta de agregados p��treos. Considere-se ainda, que a proximidade de usinas termoel��tricas, geradoras de grandes quantidades de cinzas, facilita a utiliza����o desde rejeito, o que diminui o passivo ambiental. Para o estudo dos materiais foi necess��ria a caracteriza����o das jazidas de areia de Rio Grande, das cinzas da Usina Termoel��trica de Candiota e das cinzas da queima do carv��o do secador de gr��os da empresa Bianchini localizada em Rio Grande. Foram realizados ensaios de granulometria, peso espec��fico, equivalente de areia e o ensaio Goldbeck. Com o objetivo de analisar o comportamento mec��nico das misturas foram realizados os ensaios Marshall, m��dulo resiliente, resist��ncia �� compress��o e �� tra����o e de desgaste de misturas betuminosas. Com os resultados dos ensaios citados, realizou-se a an��lise param��trica, atrav��s do programa de diferen��as finitas Elsym 5, para dimensionar diversos tipos de pavimentos, onde as vari��veis foram os teores de CAP do revestimento e as porcentagens de cal das misturas de cinza-cal. Concluiu-se ent��o, que a utiliza����o das misturas de areia-asfalto e cinza-cal s��o satisfat��rias para pavimentos com baixo volume de tr��fego, salientando os problemas de se trabalhar com as misturas a frio, devido ao elevado tempo de cura. A constru����o de um trecho experimental surge como sugest��o para analisar o desempenho destes pavimentos quanto �� durabilidade e a resist��ncia �� derrapagem.

Concentra����o de part��culas minerais grossas de fluorita em coluna de flota����o

Este estudo tem por objetivo definir um sistema de flota����o em coluna para ser utilizado, em um sistema rougher, para flotar part��culas grossas de fluorita. Para esse fim, foi proposta uma detalhada investiga����o de par��metros que poderiam influenciar o processo de flota����o de part��culas grossas. Foram definidos dois perfis granulom��tricos com alto conte��do de grossos em compara����o �� granulometria convencional, e foi analisada a varia����o dos par��metros de separa����o (recupera����o e teor) em fun����o de determinados par��metros operacionais, como concentra����o do agente coletor (tall oil), velocidade superficial do ar, concentra����o de s��lidos na polpa de alimenta����o, velocidade superficial de ��gua de bias e de ��gua de lavagem. Nesse trabalho, a inova����o proposta �� a utiliza����o da coluna de flota����o para a concentra����o de part��culas grossas em uma etapa rougher, trabalhando em regime de bias negativo (velocidade de alimenta����o maior que a velocidade de rejeito), como aplica����o e otimiza����o de um sistema de flota����o r��pida (tipo flash flotation) em coluna curta. Os resultados obtidos em coluna mostram que, mesmo com uma granulometria grossa, �� poss��vel atingir valores de recupera����o e teor semelhantes aos anotados na flota����o de finos. Nos ensaios com bias negativo (0,3 cm/s), foram registrados teores acima de 85% de fluorita nos concentrados, com recupera����es em torno de 70%. Os teores de s��lica e carbonato foram menores em compara����o a um sistema convencional, em escala de bancada. Os ensaios com adi����o de ��gua de bias tamb��m apresentaram bons resultados metal��rgicos. Nesses ensaios a mobilidade das bolhas de ar apresentou um aumento, uma vez que o fluxo ascendente de ��gua de bias ajudou a diminuir o conte��do de ar na zona de cole����o. Esse efeito foi comprovado pelos menores valores de hold up. O ensaio com bias negativo e ��gua de lavagem, aqui considerado como um indicativo para novos estudos, mostrou um efeito negativo da ��gua com rela����o �� recupera����o, mas bastante positivo com rela����o �� seletividade, uma vez que baixos valores de teor de s��lica e carbonato foram observados, sendo que nesse sistema uma ��nica etapa rougher foi suficiente para a obten����o de fluorita tipo cer��mico. A partir dos resultados, �� poss��vel afirmar que a coluna de flota����o, operando em regime de bias negativo, se mostra um equipamento eficiente na recupera����o de part��culas minerais grossas, podendo ser considerada uma rota tecnicamente adequada para o aproveitamento, concentra����o e controle de qualidade de min��rios, como o de fluorita.

Emprego da sulfata����o na recupera����o de metais de lodos galv��nicos

Este trabalho relata um estudo de sulfata����o, em escala laboratorial, com objetivo de propor um tratamento para a recupera����o seletiva de determinados metais presentes em lodos galv��nicos (LG). Os metais de interesse s��o cobre, zinco e n��quel e o agente promotor da sulfata����o �� a pirita, obtida de rejeitos de carv��o mineral. A particularidade deste tratamento �� o emprego simult��neo de dois res��duos perigosos como mat��riasprimas. Estes res��duos s��o gerados em grande quantidade em s��tios de extra����o de carv��o (rejeito piritoso) e empresas galv��nicas (lodo galv��nico). Os res��duos foram caracterizados por fluoresc��ncia de raios X (XRF), distribui����o granulom��trica e percentual de umidade. A caracteriza����o qu��mica apresentou lodos com alta concentra����o de cobre, maior do que 14% (base seca). Na etapa de sulfata����o, o lodo galv��nico foi misturado com o rejeito piritoso e os par��metros avaliados foram: raz��o lodo galv��nico/rejeito piritoso, temperatura de sulfata����o e tempo de patamar. Depois da sulfata����o, o produto da rea����o foi lixiviado com ��gua, em temperatura ambiente, por 15 min. Nesta etapa hidrometal��rgica, os par��metros vari��veis foram tempo de lixivia����o e concentra����o de s��lidos na polpa.As condi����es que melhor refletem o compromisso de recuperar os metais de interesse e a viabilidade econ��mica do processo foram alcan��ados com a raz��o 1:0,4 lodo galv��nico/rejeito piritoso, 90 min de patamar e 550��C de temperatura de sulfata����o, para a etapa pirometal��rgica e 15 min de lixivia����o e 14g.L-1 de s��lidos em polpa como condi����es hidrometal��rgicas. Estas condi����es propiciaram a recupera����o de 60% de zinco, 49% de n��quel e 50% de cobre.

Indicadores de Juruti: para onde caminha o desenvolvimento do munic��pio

Apresentamos aqui o primeiro monitoramento dos Indicadores de Juruti, fruto de um trabalho do Centro de Estudos em Sustentabilidade da Funda����o Getulio Vargas (GVces) em conjunto com a popula����o de Juruti, Par��, e apoio da Alcoa. A origem deste trabalho remonta a 2005, quando a Alcoa convidou a Funda����o Getulio Vargas e o Fundo Brasileiro para a Biodiversidade (Funbio) a apresentar uma proposta de modelo de desenvolvimento local de longo prazo para Juruti, que �� ��poca enfrentava o in��cio de grandes e profundas mudan��as em sua realidade, com a chegada da empresa para um projeto de minera����o na regi��o. O modelo apresentado, denominado "Juruti Sustent��vel", parte de quatro premissas e um trip�� de interven����o. A primeira premissa �� a participa����o ampla e efetiva da sociedade. A segunda assume que as transforma����es geradas pela implanta����o da mina de bauxita em Juruti extrapolam os limites municipais. A terceira, que essas transforma����es se d��o dentro de um contexto de din��micas de desenvolvimento regional. A quarta premissa �� a necessidade de uma cont��nua internaliza����o da sustentabilidade dentro da empresa. O trip�� de interven����o contempla a cria����o e articula����o de um espa��o de mobiliza����o social, a constru����o de indicadores para monitorar as transforma����es sociais, ambientais e econ��micas de Juruti e regi��o, e a forma����o de um fundo de apoio a projetos de desenvolvimento local.

An��lise microestrutural de misturas cer��micas de gr��s porcelanato com adi����o de chamote de telhas cer��micas

MELO, Maxymme Mendes de ; PINHEIRO, Andrea Santos ; NASCIMENTO, R. M. ; MARTINELLI, Antonio Eduardo ; DUTRA, Ricardo Peixoto Suassuna ; MELO, Marcus Ant��nio de Freitas . An��lise microestrutural de misturas cer��micas de gr��s Porcelanato com adi����o de chamote de telhas cer��micas. Cer��mica (S��o Paulo. Impresso), v. 55, p. 356-364, 2009

Formula����o e caracteriza����o de mat��rias-primas para revestimento cer��mico Semi-Poroso com adi����o de chamote de telhas

The ceramics industry in Piau�� is nowadays with 55 industries where 11 are in Teresina which is the mainstream of the state, producing 55 million shingles; in which 10 % is of this production is wasted being sometimes thrown on the margins of rivers, roads and highways provoking an environmental degradation. The main goal of this work is to verify the potential of producing semi porous ceramic using grog of shingles, on the first part of this work bodies-of-proof were produced from a basic formula of an industry, doping it with 5 %, 10 %, 15 % and 20 % in mass and in the second part of this work some bodies-of-proof were produced from a formula where one raw material was substituted by 50 % of grog and another substituting it all by grog, bodies-of-proof made of a basic formula previously announced was used for experiment control.The grog and the raw materials were characterized by: particle size analysis , thermal differential analysis, X ray diffraction , X ray fluorescence, an thermal gravimetric analysis and rational analyses. The bodies-of-proof were sintetisized in an industrial oven obeying the normal cycle adopted by an industry, with peak temperatures of 1135 oC and a fast burning cycle of 25 minutes having as energetic fuel liquefied petroleum gas . The pieces that were obtained by this were submersed in rehearsed physics of: water absorption of, apparent specific mass, apparent porosity, lineal retraction, rupture tension to the flexural and dilatometry; mineralogical analysis for X ray diffraction; and microstructural for electronic microscope of sweeping. For all the formulas with addition of grog, superior priorities to the requested by the requirements for semi porous and for the formula to F2-2,5 superior priorities to standard formulas which justifies the incorporation of the shingles in mass for the semi porous ceramic

S��ntese e caracteriza����o de peneiras moleculares mesoporosas do tipo MCM-41 e AlMCM-41 a partir de fontes alternativas de s��lica e de alum��nio

The mesoporous molecular sieves of MCM-41 and AlMCM-41 type are considered as promising support for metal in the refining processes of petroleum-based materials as catalysts and adsorbents for environmental protection. In this work the molecular sieves MCM-41 and AlMCM-41 were synthesized by replacing the source of silica conventionally used, for quartz, an alternative and abundant, and the use of waste from the production of diatomaceous earth, an aluminum-silicate, as a source aluminum, due to abundant reserves of diatomaceous earth in the state of Rio Grande do Norte in the city of Cear��-Mirim, with the objective of producing high-value materials that have similar characteristics to traditional commercial catalysts in the market. These materials were synthesized by the method of hydrothermal synthesis at 100 �� C for 7 days and subjected to calcination at 500 �� C for 2 hours under flow of nitrogen and air. The molecular sieves were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and thermogravimetric analysis (TG), adsorption of N2 (BET and BJH methods), spectroscopy in the infra red (FTIR), microscopy scanning electron (SEM) and transmission electron microscopy (TEM). The analysis indicated that the synthesized materials showed characteristic hexagonal structure of mesopores materials with high specific surface area and sort and narrow distribution of size of pores

Adi����o de res��duo cer��mico em pastas geopolim��ricas para cimenta����o de po��os de petr��leo

The development of activities the of oil and gas sector have promoted the search for suitable materials for cementing oil wells. In the state of the Rio Grande do Norte, the integrity of the cement sheath tends to be impaired during steam injection, a procedure necessary to increase oil recovery in reservoirs with low-viscosity oil. The geopolymer is a material that can be used as alternative cement, since it has been used in the production of fire-resistant components, building structures, and for the control of toxic or radioactive residues. Geopolymers result from condensation polymer alkali aluminosilicates and silicates resulting three-dimensional polymeric structures. They are produced in a manner different from that of Portland cement, which is made an activating solution that is mixed with geopolymer precursor. Among the few works studied allowed us to conclude that the pastes prepared with metakaolin as precursor showed better performance of its properties. Several studies show the addition of waste clay as a means of reducing cost and improving end of the folder properties. On this basis, the goal is to study the influence of the addition of ceramic waste in geopolymer paste. To develop the study of rheology tests were carried out, filtered, thickening time, compressive strength, free water, specific gravity and permeability, according to the American Pretoleum Institute (API). The results for all formulations studied show that the folders have high mechanical strength to a light paste; low filtrate volume, absence of free water, very low permeability, slurry, consistent with a light paste, and thickening time low that can be corrected with the use of a retardant handle. For morphological characterization, microstructural, physical, chemical and thermal tests were carried out by XRD, MEV, DTA, TG, FTIR. In the trial of XRD, it was found that geopolymer is an amorphous material, with a peak of crystalline kaolinite. In tests of TG / DTA, revealed the presence of a significant event, which represents the mass loss related to water, and also observed the reduction of weight loss by increasing the concentration of ceramic waste. In the trial of MEV, we found a uniform matrix without the presence of other phases. In the trial of FT-IR, we observed the presence of the band related to water. From all results it was determined that the optimum concentration range of use is between 2.5 and 5% of waste ceramic

Impregna����o de metais em xisto retortado para uso como adsorventes

Concern with the environment has lead to an increase in the research for new adsorption techniques, low cost adsorvent materials and with high availability. Many works search the development of higher selectivity modified adsorvents. The Brazil has the second world reserve of oiled shale, because of it, the use of that reject is of great interest. This study has the goal of characterize and analyze the retorted shale, reject of the pirobetuminous shale pyrolysis, and the retorted shale modified through the humid impregnation method, wich the precursors were the metals nitrates ( Cobalt, Nickel and Copper), to the usage has adsorvent materials. The samples were characterized chemically, textually and structurally by the X ray fluorescence (XRF), BET, X ray diffraction (XRD) and scanning electronic microscopy (SEM) techniques. The impregnated samples showed a reduction in the superficial area and in the pore volume when compared with the retorted shale. Besides that, diffractions referred to the impregnated metals where observed in the XRD analysis, wich were the same metals detected in the XRF and SEM analysis. The materials showed homogeneity in it s composition. The results shows that the materials presents adequate adsorption characteristics

Formula����o de bloco intertravado cer��mico com adi����o de res��duos urbanos e industriais

The production of waste from urban and industrial activities is one of the factors of environmental contamination and has aroused attention of the scientific community, in the sense of its reuse. On the other hand, the city of Salvador/Ba, with approximately 262 channels, responsible for storm water runoff, produces every year, by the intervention of cleaning and clearing channels, a significant volume of sediments (dredged mud), and thus an appropriate methodology for their final destination. This study aims to assess the influence of incorporation of these tailings in arrays of clay for production of interlocked block ceramic, also known as ceramic paver. All the raw materials from the metropolitan region of Salvador (RMS) were characterized by x-ray fluorescence, x-ray diffraction, thermal analysis (TG and TDA), particle size analysis and dilatometry. With the use of statistical experimental planning technique, ternary diagram was defined in the study region and the analyzed formulations. The specimens were prepared with dimensions of 60x20x5mm��, by uniaxial pressing of 30 MPa and after sintering at temperatures of 900��, 1000�� and 1100��C the technological properties were evaluated: linear shrinkage, water absorption, apparent porosity, apparent specifies mass, flexural rupture and module. For the uniaxial compression strength used cylindrical probe body with �� 50 mm. The standard mass (MP) was prepared with 90% by weight of clay and 10% by weight of Channel sediment (SCP), not being verified significant variations in the properties of the final product. With the incorporation of 10% by weight of manganese residue (PFM) and 10% by weight of the Ceramic waste (RCB) in the mass default, in addition to adjusting the plasticity due to less waste clay content, provided increased linear firing shrinkage, due the significant concentration of K2O, forming liquid phase at low temperature, contributing to decreased porosity and mechanical resistance, being 92,5 MPa maximum compressive strength verified. After extract test leachate and soluble, the piece containing 10% of the PFM, was classified as non-hazardous and inert material according to NBR10004/04 ABNT. The results showed the feasibility on using waste, SCP, RCB and PFM clay mass, at temperatures above 900��C, paver ceramic production, according to the specifications of the technical standards, so that to exceed the 10% of the PFM, it becomes imperative to conduct studies of environmental impacts

Influ��ncia da substitui����o de areia natural por p�� de pedra no comportamento mec��nico, microestrutural e eletroqu��mico de concretos

The construction industry is one of the largest consumers of natural raw materials, and concrete is considered today the most used material wide. This accentuated consumption of natural resources has generated concern with the preservation of the environment, and has motivated various studies related to the use of resid ues, which can partially or entirely substitute, with satisfactory performance, some materials such as the aggregate, and in so doing, decrease the impact on the environment caused by the produced residues. Research has been done to better understand and improve the microstructure of concrete, as well as to understand the mechanism of corrosion in reinforced steel. In this context, this work was developed aiming at discovering the influence of the substitution of natural sand by artificial sand, with rega rd to mechanical resistance, microstructure, and durability. To obtain the electrochemical parameters, an adaptation was made to the galvanostatic electrochemical method to study the corrosion in reinforced steel. Concretes of categories 20 MPa and 40 MPa were produced, containing natural sand, and concretes of the same categories were produced with artificial sand substituting the natural sand, and with the addition of sodium nitrate and sodium chloride. Due to the use of rock dust reject (artificial sand), an evaluation was made of its environmental risk. The results indicate that the concretes of category 20 MPa present a better performance than the concrete made with natural sand, thus making it a viable substitute. For the category 40 MPa, the better performance is from the concrete containing natural sand. The adaptation of the galvanostatic electrochemical technique to the study of the corrosion of reinforced steel within concrete proved to be valid for obtaining electrochemical parameters with a high degree of reliability, considering the number of degrees of freedom

Vari��veis biom��tricas da cana-de-a����car fertilizada com res��duos org��nico e industrial e irrigada com ��gua servida e pot��vel

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Caracteriza����o f��sica e qu��mica de ��reas mineradas pela extra����o de cassiterita

O objetivo deste trabalho foi caracterizar as diferen��as ocorridas, ap��s a atividade da minera����o de cassiterita, em uma ��rea de floresta amaz��nica. As amostras foram coletadas, superficialmente, em ��rea de minera����o de cassiterita na Floresta Nacional do Jamari (RO), ao longo de uma linha compreendendo: floresta, capoeira, piso de lavra, ��rea de deposi����o de rejeito seco e ��rea de deposi����o de rejeito ��mido. em cada situa����o descrita foram coletadas cinco amostras, que serviram como repeti����o, totalizando 25. Nas amostras coletadas foram realizadas an��lises f��sicas e qu��micas. O processo de extra����o de cassiterita promoveu altera����es significativas nos atributos dos solos estudados. A mat��ria org��nica, o f��sforo dispon��vel, a densidade de part��culas e a resist��ncia �� penetra����o foram os mais alterados pelo processo de supress��o da vegeta����o original e extra����o do min��rio.

Influ��ncia da adi����o de rejeitos cer��micos nas propriedades de cer��mica vermelha da regi��o do Rec��ncavo Baiano

The study of the physical and mechanic properties is an analysis of unquestioned importance on the production of the ceramic materials. In the region of the Rec��ncavo Baiano, there are ceramic and small brick factories, that still use rudimentary techniques, where the necessity of characterization of raw materials is denounced by the quality of the final product. The present work has for objective to study the behavior of the clay proceeding from the region of the Rec��ncavo, between the cities of Candeias and Cama��ari/Ba, with addition of 5, 10 and 15% by weight of brick scraps, trying to optimize the physic and mechanical properties of the final product, aiming a better possibility of being manufactured, mechanic resistance, low linear retraction and water absorption. The brick scraps and the clay were characterized by FRX, DRX, TG, ATD and the granulometric analysis. Samples for testing where prepared by uniaxial pressing at 25Mpa, in 60x20x5mm size. The evaluated technological properties were: linear retraction, water absorption, apparent porosity and flexural strength. The samples were burned in electric oven in the temperatures of 850��, 950�� and 1050��C and compared its mechanical properties and the gresification. With addition of 15% by weight of brick scraps and burning at 900��-1000��C the samples showed properties superior to that clay