Eficácia do tratamento térmico na extração hidrometalúrgica de potássio em rochas contendo feldspato potássico / Efficiency of heat treatment in the hydrometallurgical extraction of potassium in rocks containing potassium feldspar

Os Feldspatos são tectossilicatos que contém minerais que são fontes alternativas de K para produção de fertilizantes, porém ainda sem explotação comercial em grande escala, por falta de tecnologia comercial que torne o negócio viável economicamente. Neste trabalho é avaliada a extração de potássio de rochas que contém estes minerais, após tratamento térmico prévio e subsequente extração hidrometalúrgica com H2SO4. Foram avaliadas três temperaturas: 1000°C, 1100°C e 1200°C. Para a fase hidrometalúrgica foi incluída uma amostra do minério “in natura”. Foi selecionada uma amostra contendo Microclina (59%), Sanidina (17%) e Kalsilita (20%) com teores de 20,7% de K2O e 23,5% de Al2O3. O tempo de calcinação foi de 2h para um material com granulometria 100%0,15mm. A extração de potássio foi conduzida através desolução de H2SO4 com concentração inicial de 20%, por 4h e temperatura de (85±5)°C. Os valores de extrações foram similares, com tendência de queda em 1200°C, mostrando que o tratamento térmico não propiciou nenhum benefício à recuperação hidrometalúrgica. A extração ficou entre 55% e 58%

Glauconite-bearing rocks as alternative potassium source for fertilizer by thermal processing with additives / Rochas portadoras de glauconita como fonte alternativa de potássio para fertilizantes por processamento térmico com aditivos

Glauconite (K,Na) (Fe,Al,Mg)2 (Si,Al)4 O10 (OH)2 is a green, potassium and iron hydrated phyllosilicate, monoclinic mineral. It is a secondary mineral formed from the alteration of iron-rich micas, such as biotite. It is a potential source of potassium, but still not commercialized due to lack of commercial technology that makes the business viable. The objective of this work was to evaluate the reactivity, in relation to the release of potassium, from a glauconite-containing rock, subjected to thermal alteration, with additives, at two temperatures: 800°C 900°C. The source of glauconite was the Verdete that occurs in Serra da Saudade, in the region of the municipality of Cedro de Abaeté, state of Minas Gerais, Brazil. The following additives were used:CaSO4.2H2O, CaCO3 and Na2SO4,at the mass ratio with respect to the rock: (1.0: 0.2: 0.3: 0.2). Thermal alteration was performed at 800°C900°C. After thermal alteration, the calcined samples were leached with 20% sulfuric acid (m/m). The final product was a solution containing K2SO4. At the temperature of 800°C, the potassium released reached only 11.2%. Increasing the temperature to 900°C, the extraction incresed to 40%. There was a tendency for increased potassium release at temperatures higher than 900°C. These findings highlight gave the potential forglauconite to be exploited as an alternative source of potassium for the production of fertilizer, by thermal processing with sulfating compounds

Fluoride aided potassium extraction from Verdete rock by thermal processing with ferrous sulfate heptahydrate. / Extração de potássio auxiliada por flúor da rocha de Verdete por processamento térmico com sulfato ferroso hepta-hidratado

Glauconite is a green-colored monoclinic mineral with hydrated phyllosilicate of potassium and iron. It has low resistance to weathering and is usually found in sandstones and shales, as well as in marls and impure limestones. It is a secondary mineral formed from the modification of iron-rich micas, such as biotite. Even though it is an alternative source of potassium, it is still not extracted commercially on a large scale due to the lack of commercial technology that makes the business viable economically.Ferrous sulfate heptahydrate is a residue or by-product formed during the pickling of iron and steel and also in the manufacture of titanium dioxide from the ilmenite.Iron, as a raw material for the production of reagents, is abundant in the tailings of this metal.The use of ferrous sulfate as a sulfating agent has the advantage of being more selective and less aggressive during processing, in addition to the property of being thermosensitive.Fluorine accelerates this sulfation process due to an ionic substitution action on the structure of glauconite and on compounds that prevent the reaction, such as calcium sulfate.This work has investigated the release of potassium by dissolution in a 2% (w/w)citric acid solution in water, after previous thermal and chemical processing of glauconite rock (10% K2O) from Cedro doAbaeté - MG - Brazil with ferrous sulfate heptahydrate and NaF in the ratio (1.00: 0.70: 0.01), respectively.Potassium soluble in citric acid and not soluble in water characterizes a slow acting fertilizer.Thermal processing was performed at temperatures of 500°C and 700°C for 6h in a fluidized bed oven.The selection of ferrous sulphate was based on a thermodynamic evaluation of the system.The results showed that the thermal processing of the rock and ferrous sulfate mixture alone was not effective for the release of potassium in aqueous solution and in citric acid.The extraction of potassium from raw rock in citric acid was 7%.The mixture of rock and ferrous sulfate, without fluoride, in citric acid had an extraction rate of 6.8%.However, the same mixture with addition of 29ppm of fluorine had different results, in water (20% at 700°C) and mainly in citric acid (52.1% at 700°C), increasing the availability of potassium in more than 7 times when compared to the availability of rock potassium in natura.This study confirms that the combined effects of fluorine and temperature of thermal processing increase the release of potassium from glauconite

Análise da hidroxilação de magnésia cáustica em moinho e reator CSTR / Analysis of caustic magnesia hydroxilation in CSTR reactor and mil

O hidróxido de magnésio se destaca por sua aplicação como retardante de chamas e neutralizante, sendo obtido seguido pela etapa de reação de hidroxilação do óxido de magnésio e moagem para adequação da granulometria abaixo de 45μm. A etapa de moagem a úmido se mostra essencial na produção de hidróxido de magnésio consiste em ambiente abundante em água, apresentando condição favorável para conduzir a hidroxilação. Portanto, o presente trabalho visa avaliar o comportamento da hidroxilação do óxido de magnésio em reator CSTR e em sistema de moagem a úmido. Os resultados mostraram a diminuição de tamanho médio (D50) do HM obtido no moinho em relação ao CSTR igual a 27%. Por sua vez, a conversão final do produto do moinho foi 5,22% maior que a conversão final do produto do CSTR. Logo, foi possível confirmar a viabilidade de realização da hidroxilação da magnésia cáustica em um sistema de moagem à úmido e melhorias em relação ao sistema convencional em reator CSTR. 

Water recovery from saline streams produced by electrodialysis

Advances in technologies to enable water reuse in industry have been the objective of many research efforts, mainly due to the need to reduce the use of natural resources and due to factors related to their availability. This paper evaluates the crystallization of salts from petrochemical saline waste to achieve zero water discharge by the recovery of water and dissolved salts as a solid mixture. In line with process symbiosis, the recovered water should be suitable for use as cooling water in heat exchangers. Vacuum evaporative crystallization, at the batch scale, was used to remove the salts present in the concentrated stream from reverse electrodialysis of pretreated wastewater by a biological process. The partition of organic compounds in the feed solution between the condensate and the mother liquor was obtained from measurements of the total organic carbon and total nitrogen in the solutions. The solid phases formed experimentally are compared with those predicted by chemical modelling by PHREEQC. The recovered water presented almost 50 times less total dissolved solids than the feed stream (from 2100 to 44 mg/L). Calcium sulphate hydrate, calcium sulphate and sodium chloride were the majority crystalline phases formed, in accordance with the modelling by PHREEQC.Advances in technologies to enable water reuse in industry have been the objective of many research efforts, mainly due to the need to reduce the use of natural resources and due to factors related to their availability. This paper evaluates the crystalli363386394FAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORsem informaçãosem informaçãosem informaçãoAit Hsine, E., Benhammou, A., Pons, M.N., Water resource management in soft drink industry-water use and wastewater generation (2005) Environ Technol, 26, pp. 1309-1316Garcia, N., Moreno, J., Cartmell, E., Rodriguez-Roda, I., Judd, S., The application of microfiltration-reverse osmosis/ nanofiltration to trace organics removal for municipal wastewater reuse (2013) Environ Technol, 34, pp. 3183-3189Diya-Uddeen, B.H., Daud, W.M.A.W., Abdul Aziz, A.R., Treatment technologies for petroleum refinery effluents: A review (2011) Process Saf Environ Prot, 89, pp. 95-105Santiago, V.M.J., (2010) Pesquisas e Implantacao de Tecnologias de Ponta No Tratamento e Reuso de Efluentes Hidricos de Refinarias, , VII Simposio Internacional de Qualidade Ambiental. Porto Alegre RSKapdan, I.K., Boylan, B., Batch treatment of saline wastewater by Halanaerobium lacusrosei an anaerobic packed bed reactor (2009) J Chem Technol Biotechnol, 84, pp. 34-38Arkhangelsky, E., Wicaksana, F., Chou, S., Al-Rabiah, A.A., Al-Zahrani, S.M., Wang, S., Effect of scaling and cleaning on the performance of forward osmosis hollow fibers membranes (2012) J Membr Sci, 415-416, pp. 101-108Dreiser, C., Bart, H., Mineral scale control in polymer film heat exchanger (2014) Appl Thermal Eng, 65, pp. 524-529Ahmed, M., Arakel, A., Hoey, D., Coleman, M., Integrated power, water and salt generation: A discussion paper (2001) Desalination, 134, pp. 37-45Ahmed, M., Shayya, W.H., Hoey, D., Al-Handaly, J., Brine disposal from reverse osmosis desalination plants in Oman and the United Arab Emirates (2001) Desalination, 133, pp. 135-147Morillo, J., Usero, J., Rosado, D., El Bacuori, H., Riaza, A., Bernaola, F.J., Comparative study of brine management technologies for desalination plants (2014) Desalination, 336, pp. 32-49Turek, M., Dydo, P., Klimed, R., Salt production from coal-mine brine in ED-evaporation-crystallization system (2005) Desalination, 184, pp. 439-446Lefebvre, O., Moletta, R., Treatment of organic pollution in industrial saline wastewater: A literature review (2006) Water Res, 40, pp. 3671-3682Ji, X., Curcio, E., Al Obaidani, S., Di Profio, G., Membrane distillation-crystallization of seawater reverse osmosis brines (2010) Separation Purif Technol, 71, pp. 76-82Reddy, S.T., Lewis, A.E., Witkamp, G.J., Van Spronsen, J., Recovery of Na2SO4·10H2O from a reverse osmosis retentate by eutectic freeze crystallization technology (2010) Chem Eng Res des, 88, pp. 1153-1157Randall, D.G., Nathoo, J., Lewis, A.E., A case study for treating a reverse osmosis brine using eutectic freeze crystallization - Approaching a zero waste process (2011) Desalination, 266, pp. 256-262Lewis, A.E., Nathoo, J., Thomsen, K., Kramer, H.J., Witkramp, G.J., Reddy, S.T., Randall, D.G., Design of eutectic freezecrystallization process for multicomponent waste water stream (2010) Chem Eng Res des, 88, pp. 1290-1296(2005) Site Ministerio Do Meio Ambiente [Internet], , http://www.mma.gov.br/, Resolucao CONAMA 357. 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Alternativas para o tratamento de efluentes da indústria galvânica Alternatives for the galvanic wastewater treatment

Os métodos de precipitação química, cristalização e extração líquido-líquido foram aplicados visando propor alternativas para o tratamento de efluentes líquidos gerados pela indústria de galvanoplastia. Efluentes de diversas empresas do setor, localizadas no estado de Minas Gerais (Brasil), foram coletados e caracterizados. O efluente estudado, proveniente de empresa de galvanização de zinco a quente, continha cerca de 90 g/L de ferro total, 35 g/L de zinco e menores quantidades de Al, Ni e Cu, em meio ácido clorídrico (pH = 0,6). A separação seletiva entre ferro e zinco não se mostrou eficiente por precipitação, sendo a técnica adequada somente no tratamento do efluente, ao contrário da cristalização e extração líquido-líquido utilizando-se TBP como agente extratante. A integração destas técnicas ainda requer estudos mais detalhados visando à otimização de custos e das condições operacionais.<br>Separation methods such as chemical precipitation, crystallization and liquid-liquid extraction have been investigated aiming to treat effluents generated by the galvanic industry. Effluent samples generated by several companies located in the state of Minas Gerais (Brazil) were collected and chemically characterized. For this work, a typical zinc hot-dip galvanizing effluent containing about 90 g/L of total iron, 35 g/L of zinc and minor amounts of Al, Ni, Cu, in HCl medium (pH = 0.6) was treated. A selective separation between metals zinc and iron was not achieved by chemical precipitation, which was found adequate to threat water only. On contrary, zinc and iron was separated very efficiently by crystallization and liquid-liquid extraction using TBP as extractant agent. The integration of these methods to recover zinc and iron from effluent still requires more detailed studies

Características do acesso e utilização de serviços odontológicos em municípios de médio porte Characteristics of the access and utilization of public dental services in medium-sized cities

Este estudo de corte transversal descreve as principais características de acesso e utilização de serviços odontológicos básicos e especializados em dois municípios de médio porte da Bahia com 100% de cobertura da Estratégia de Saúde da Família. Realizou-se um inquérito com 2.539 indivíduos de idade acima de 15 anos em 952 domicílios. As principais variáveis analisadas foram a necessidade de saúde bucal percebida, a procura pelo serviço, a barreira de acesso organizacional e o tipo de serviço e o procedimento utilizado. A utilização de serviços públicos odontológicos especializados foi de 11,7% e básicos de 26%. No município com maior utilização de serviços públicos odontológicos, foi menor o uso de serviços privados. A principal barreira de acesso situou-se na AP (Atenção Primária), entre 5,0% e 15,2%. Observou-se pouca interface da atenção secundária com a AP já que apenas 16,6% dos usuários retornaram a esse nível de atenção. Pode-se concluir que a principal barreira de acesso, em municípios com realidades organizacionais e geográficas específicas parece se situar na AP. Ações preventivas individuais foram pouco relatadas. Recomenda-se a redução de barreiras de acesso na AP, bem como a instituição de um protocolo que estimule a longitudinalidade do cuidado nesse nível.<br>This cross-sectional study sought to describe the main characteristics of access and utilization of primary and specialized public dental services in two medium-sized cities in Bahia with 100% coverage of the Family Health Program. A survey of 952 households and 2.539 individuals aged over 15 years was conducted. The main variables analyzed were: perceived oral health needs, demand for the service, barriers of organizational access and the type of service and procedure utilized. The use of specialized public dental services was of 11.7% and primary care was 26%. In the city where there was greater use of public dental services, there was less use of private services. The main barrier to access remained in primary care (from 5.0% to 15.2%). There was little interface between secondary care a primary care, as only 16.6% of users returned to this level of care. In conclusion, the main barrier to access in cities with specific organizational and geographic realities appears to be in primary dental care. Individual preventive actions were little reported. It is recommended that barriers to access in primary care be eliminated, and also that a protocol (clinical guides) be established to foster the continuity and longitudinality of primary dental care