Basic oxygen furnace slag as a treatment material for pathogens: Contribution of inactivation and attachment in virus attenuation

Basic oxygen furnace (BOF) slag media were studied as a potential treatment material in on-site sanitation systems. Batch and column studies were conducted to evaluate attenuation of the bacteriophage PR772 and 0.190 mu m diameter microspheres by BOF media, and to delineate the relative contributions of two principle processes of virus attenuation: inactivation and attachment. In the batch studies, conducted at 4 degrees C, substantial inactivation of PR772 did not occur in the pH 7.6 and 9.5 suspensions. At pH 11.4, bimodal inactivation of PR772 was observed, at an initial rate of 2.1 log C/C(0) day(-1) for the first two days, followed by a much slower rate of 0.124 log C/C(0) day(-1) over the following 10 days. Two column studies were conducted at 4 degrees C at a flow rate of 1 pore volume day(-1) using two slag sources (Stelco, Ontario; Tubarao, Brazil) combined with sand and pea gravel. In both column experiments, the effluent microsphere concentration approached input concentrations over time (reductions of 0.1-0.2 log C/C(0)), suggesting attachment processes for microspheres were negligible. Removal of PR772 virus was more pronounced both during the early stages of the experiments, but also after longer transport times (0.5-1.0 log C/C(0)). PR772 reduction appeared to be primarily as a result of virus inactivation in response to the elevated pH conditions generated by the BOF mixture (10.6-11.4). On-site sanitation systems using BOF media should be designed to maintain sufficient contact time between the BOF media and the wastewater to allow sufficient residence time of pathogens at elevated pH conditions. (C) 2009 Published by Elsevier Ltd.

Estudo da viabilidade técnica da utilização de escórias de aciaria do processo LD como adição em cimentos

A reciclagem de resíduos apresenta-se como uma alternativa adequada com relação à preservação dos recursos naturais e do meio ambiente. As escórias de aciaria são resíduos siderúrgicos originados na fabricação do aço, e são geradas em grandes quantidades. Estes resíduos são estocados nos pátios siderúrgicos, onde permanecem, na sua maioria, sem qualquer destino. Normalmente, as escórias de aciaria são volumetricamente instáveis, apresentando características expansivas, e por esta razão, a aplicação das mesmas em materiais de construção torna-se restrita. Esta pesquisa tem como objetivo estudar a viabilidade técnica do uso das escórias de aciaria LD como adição em cimentos, propondo um método de estabilização por meio de granulação por resfriamento brusco destas escórias, buscando, desta forma, a eliminação do fenômeno da expansão, e visando a melhoria das características destes resíduos. No processo de estabilização, a escória líquida foi granulada em uma usina siderúrgica. Estudos complementares de granulação foram realizados nos laboratórios da UFRGS, empregando-se escórias refundidas. A granulação por resfriamento brusco favoreceu a redução do CaOlivre, a eliminação do MgO na forma de periclásio, e a eliminação do bC2S das escórias, considerados agentes causadores da expansão. No entanto, a elevada basicidade da escória LD dificulta a formação da estrutura vítrea e a separação da fração metálica após o resfriamento brusco. Foram realizados ensaios de expansão das escórias, atividade pozolânica, e resistência mecânica de argamassas com escórias granuladas. O resfriamento brusco proporcionou a eliminação da expansão e o desenvolvimento das propriedades pozolânicas/cimentícias da escória granulada. Como adição em cimentos, do ponto de vista da resistência mecânica, as argamassas compostas com escórias granuladas e clínquer apresentaram níveis de resistência à compressão axial compatíveis com as especificações referentes ao cimento Portland composto, apesar destes resultados serem inferiores aos obtidos para as argamassas de referência.

Viabilidade técnica da fabricação de cimento com mistura de escória de aciaria LD e resíduo de granito

Esse trabalho estuda a viabilidade técnica da fabricação de cimento com uma mistura de resíduo proveniente da serragem de blocos de granito e escória de aciaria LD. Para isso, foi preparada uma mistura desses materiais de modo que a relação %CaO / %SiO2 fosse 1,2. Essa mistura foi fundida e resfriada rapidamente em água. A amostra foi caracterizada e o difratograma de raios X mostrou um material amorfo e a presença das fases mineralógicas Akermanita e Gehlenita, as quais são consideradas como as fases mineralógicas ideais para a atividade hidráulica. Essa mistura foi adicionada ao clínquer para a fabricação de cimento. Com o cimento fabricado, foram feitos ensaios cujos resultados são apresentados e comparados com os valores obtidos para o cimento de alto-forno. Esses resultados indicam a viabilidade técnica da utilização da mistura na fabricação de cimento.

Macronutrients in Marandu Palisade Grass as Influenced by Lime, Slag, and Nitrogen Fertilization

Soil acidity is one of the main limiting factors for the growth of pasture grasses in Brazilian soils. In addition to lime, slag can be used to correct soil acidity and help plants to absorb nutrients in adequate amounts. The objective of this experiment was to evaluate, under greenhouse conditions, the effects of slag and lime plus nitrogen (N) on marandu palisade grass plants` nutritional status as well as the absorption of macronutrients submitted to two cuts. The treatments consisted of two corrective materials (slag and lime), three corrective material rates (0.81, 1.61, and 3.22 g dm-3 of ECaCO3), three N rates (75, 150, and 300 mg dm-3) plus a control treatment, with four replications. Macronutrient contents in the forage plants were found to be present in adequate levels. The mean value of N accumulated in the shoot was 40.1 mg per plant, phosphorus (P) was 4.6 mg per plant, potassium (K) was 38.6 mg per plant, calcium (Ca) was 7.3 mg per plant, magnesium (Mg) was 6.7 mg per plant, and sulfur (S) was 3.5 mg per plant at the first cut. At the second cut, the nutrient accumulations values were N 50.8 mg per plant, P 6.3 mg per plant, K 20.7 mg per plant, Ca 21.6 mg per plant, Mg 24.0 mg per plant, and S 4.7 mg per plant. Macronutrients accumulation in the shoot of grass increased with the addition of both the correctives as well as the N rates.

Short-term experimental data of drying shrinkage of ground granulated blast-furnace slag cement concrete

This paper presents results of laboratory testing of unrestrained drying shrinkage during a period of 154 days of different concrete mixtures from the Brazilian production line that utilize ground granulated blast-furnace slag in their compositions. Three concrete mixtures with water/cement ratio of 0.78(M1), 0.41(M2), and 0.37(M3) were studied. The obtained experimental data were compared with the analytical results from prediction models available in the literature: the ACI 209 model (ACI), the B3 model (B3), the Eurocode 2 model (EC2), the GL 2000 model (GL), and the Brazilian NBR 6118 model (NBR), and an analysis of the efficacy of these models was conducted utilizing these experimental data. In addition, the development of the mechanical properties (compressive strength and modulus of elasticity) of the studied concrete mixtures was also measured in the laboratory until 126 days. From this study, it could be concluded that the ACI and the GL were the models that most approximated the experimental drying shrinkage data measured during the analyzed period of time.

Characterization of mixed waste of granite and LD slag

This study focuses on the technical feasibility of the utilization of waste from the cutting of granite to adjust the chemical composition of slag from steelworks LD, targeting the addition of clinker Portland cement. For this, chemical characterization of the waste, its mixture and fusion was performed, obtaining a CaO/SiO(2) relationship of around 0.9 to 1.2 for the steelworks slag. We selected samples of the waste, mixed, melted and cooled in water and in the oven. Samples cooled in water, after examining with X-ray difractrograms, had been predominantly amorphous. For samples cooled in the furnace, which had vitreous, there was the presence of mineralogical phases Akermanita and Gehlenita, which is considered as the ideal stage for the mineral water activity of the slag. The adjustment of the chemical composition of the slag from steel works by the addition of waste granite was efficient, transforming the waste into a product that is the same as blast furnace slag and can be used in the manufacture of cement.

Drying and autogenous shrinkage of pastes and mortars with activated slag cement

Activated slag cement (ASC) shows significantly higher shrinkage than ordinary Portland cement agglomerates. Cracking generated by shrinkage is one of the most critical drawbacks for broader applications of this promising alternative binder. This article investigates the relationship between ASC hydration, unrestrained drying and autogenous shrinkage of mortar specimens. The chemical and microstructure evolution due to hydration were determined on pastes by thermogravimetric analysis, conduction calorimetry and mercury porosimetry. Samples were prepared with ground blast furnace slag (BFS) activated with sodium silicate (silica modulus of 1.7) with 2.5, 3.5 and 4.5% of Na2O, by slag mass. The amount of activator is the primary influence on drying and autogenous shrinkage, and early hydration makes a considerable contribution to the total result, which increases with the amount of silica. Drying shrinkage occurred in two stages, the first caused by extensive water loss when the samples were exposed to the environment, and the second was associated with the hydration process and less water loss. Due to the refinement of ASC porous system, autogenous shrinkage is responsible for a significant amount of the total shrinkage. (C) 2007 Elsevier Ltd. All rights reserved.

Mechanical properties, drying and autogenous shrinkage of blast furnace slag activated with hydrated lime and gypsum

This article reports the characteristics of blast furnace slag (BFS) pastes activated with hydrated lime (5%) and hydrated lime (2%) plus gypsum (6%) in relation to compressive strength, shrinkage (autogenous and drying) and microstructure (porosity, hydrated products). The paste mixtures were characterized using powder X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and thermogravimetric analysis (TG/DTG). BSF activated with lime and gypsum (LG) results in larger amounts of ettringite when compared with BFS activated with lime (L). Although the porosities of the L and LG mixtures were about the same, there was a greater pore refinement for the BFS activated with lime, with an increase in mesopores volume with age. The presence of ettringite and the higher volumes of macropores cause the compressive strength of BSF activated with hydrated lime plus gypsum to be smaller than that of BFS activated with lime. For both chemical activators, compressive strength developed slowly at early ages. Autogenous and drying shrinkage were greater for the BFS activated with lime, believed to result from the more refined porous structure in comparison with the mixture activated with gypsum plus lime. (c) 2010 Elsevier Ltd. All rights reserved.

Coupled experimental and thermodynamic modeling studies for metallurgical smelting and coal combustion slag systems

An extensive research program focused on the characterization of various metallurgical complex smelting and coal combustion slags is being undertaken. The research combines both experimental and thermodynamic modeling studies. The approach is illustrated by work on the PbO-ZnO-Al2O3-FeO-Fe2O3-CaO-SiO2 system. Experimental measurements of the liquidus and solidus have been undertaken under oxidizing and reducing conditions using equilibration, quenching, and electron probe X-ray microanalysis. The experimental program has been planned so as to obtain data for thermodynamic model development as well as for pseudo-ternary Liquidus diagrams that can be used directly by process operators. Thermodynamic modeling has been carried out using the computer system FACT, which contains thermodynamic databases with over 5000 compounds and evaluated solution models. The FACT package is used for the calculation of multiphase equilibria in multicomponent systems of industrial interest. A modified quasi-chemical solution model is used for the liquid slag phase. New optimizations have been carried out, which significantly improve the accuracy of the thermodynamic models for lead/zinc smelting and coal combustion processes. Examples of experimentally determined and calculated liquidus diagrams are presented. These examples provide information of direct relevance to various metallurgical smelting and coal combustion processes.

Predicting coal ash slag flow characteristics (viscosity model for the Al2O3-CaO-'FeO'-SiO2 system)

A model has been developed which enables the viscosities of coal ash slags to be predicted as a function of composition and temperature under reducing conditions. The model describes both completely liquid and heterogeneous, i.e. partly crystallised, slags in the Al2O3-CaO-'FeO'-SiO2 system in equilibrium with metallic iron. The Urbain formalism has been modified to describe the viscosities of the liquid slag phase over the complete range of compositions and a wide range of temperatures. The computer package F * A * C * T was used to predict the proportions of solids and the compositions of the remaining liquid phases. The Roscoe equation has been used to describe the effect of presence of solid suspension (slurry effect) on the viscosity of partly crystallised slag systems. The model provides a good description of the experimental data of fully liquid, and liquid + solids mixtures, over the complete range of compositions and a wide range of temperatures. This model can now be used for viscosity predictions in industrial slag systems. Examples of the application of the new model to coal ash fluxing and blending are given in the paper. (C) 2001 Elsevier Science Ltd. All rights reserved.

Avaliação e substituição de produtos químicos no sector BOF da Swedwood Portugal

A crescente preocupação com aspectos ambientais tornou-se uma questão incontornável para as empresas. Assim, a legislação aplicável obriga a maior controlo de qualquer tipo de perigo que ponha em causa a saúde humana ou o ambiente. Deste modo, a Swedwood Portugal é obrigada a implementar algumas medidas de controlo dos produtos químicos. Assim, os objectivos deste estágio curricular fundamentamse em identificar, avaliar e substituir ou minimizar os impactos dos produtos químicos (PQ’s) que, de acordo com especificações REACH (Regulamento da Comissão Europeia, relativo a Registo, Avaliação, Autorização e restrição de substâncias Químicas) e da Swedwood Internacional não podem ser utilizados. Como tal, o trabalho descrito nesta dissertação foi dividido em várias etapas. A primeira etapa consistiu em identificar todos os PQ’s utilizados no sector Board On Frame (BOF) da Swedwood Portugal. Feito este inventário, foi então criada uma base de dados em formato Microsoft Office Access que permitiu compilar a informação mais relevante dos PQ’s, para uma consulta mais simples e expedita, substituindo a já existente e desactualizada base de dados de PQ’s em formato Microsoft Office Excel. No total foram inventariados 243 PQ’s. Contudo, não foi possível obter as Fichas de Segurança de todos e, por isso, apenas 185 foram registados na base de dados. Estes 185 PQ’s existentes no sector BOF da Swedwood Portugal, foram submetidos a uma avaliação das substâncias que os compõem de acordo com uma ferramenta informática criada pela Swedwood Internacional – Substitution Evaluation Key (SEK). Esta ferramenta usa três listas europeias de substâncias químicas que permitem a avaliação de produtos químicos indirectos: Substances of Very High Concern (SVHC) da Agência Europeia de Produtos Químicos (ECHA), Substitute It Now (SIN) da ChemSec (Organização sueca dedicada ao ambiente) e PRIO da Agência Sueca de Produtos Químicos (Kemi). As três listas incluem substâncias de carácter de tal forma perigoso que a sua utilização deve ser restringida ou até eliminada. Logo, os PQ’s indirectos que contenham substâncias presentes em, pelo menos, uma destas listas devem ser imediatamente substituídos por outros cuja avaliação seja positiva. Por outro lado, para produtos químicos directos, as restrições encontram-se numa especificação imposta pela IKEA, IOS-MAT-0066. Concluída a avaliação, foi então necessário encontrar alternativas viáveis aos PQ’s avaliados negativamente. Como tal, a primeira abordagem consistiu em contactar os fabricantes dos PQ’s a substituir de modo a que estes pudessem apresentar as suas próprias alternativas. Caso estes não apresentassem alternativas viáveis, então contactarse- iam novos fornecedores. Dos 185 PQ’s registados na base de dados e avaliados, 30 produtos químicos indirectos existentes nas fábricas não obedeciam aos critérios impostos pela SEK, estando os produtos químicos directos todos de acordo com as imposições da IOS-MAT-0066. Os 30 PQ’s indirectos do Sector BOF da Swedwood Portugal que incluem as substâncias químicas com carácter perigoso apresentam características Cancerígenas, Mutagénicas e tóxicas para a Reprodução (CMR), irritantes e/ou sensibilizantes e perigosas, a longo prazo, para o ambiente. Para estes PQ’s foram apresentadas alternativas viáveis no que concerne a impactos para a saúde ou para o ambiente e os respectivos custos associados (admitindo quantidades mínimas vendidas). Contudo, não foi possível em tempo útil testar estas alternativas no funcionamento da empresa de modo a avaliar a sua eficiência técnica.

Use of steel slag to neutralize acid mine drainage (AMD) in sulfidic material from a uranium mine

Acid Mine Drainage (AMD) is one of the main environmental impacts caused by mining. Thus, innovative mitigation strategies should be exploited, to neutralize acidity and prevent mobilization of trace elements in AMD. The use of industrial byproducts has been considered an economically and environmentally effective alternative to remediate acid mine drainage. Therefore, the objective of this study was to evaluate the use of steel slag to mitigate acid mine drainage in a sulfidic material from a uranium mine, as an alternative to the use of limestone. Thus, increasing doses of two neutralizing agents were applied to a sulfidic material from the uranium mine Osamu Utsumi in Caldas, Minas Gerais State. A steel slag from the company ArcelorMittal Tubarão and a commercial limestone were used as neutralizing agents. The experiment was conducted in leaching columns, arranged in a completely randomized, [(2 x 3) + 1] factorial design, consisting of two neutralizing agents, three doses and one control, in three replications, totaling 21 experimental units. Electrical conductivity (EC), pH and the concentrations of Al, As, Ca, Cd, Cu, Fe, Mn, Ni, S, Se, and Zn were evaluated in the leached solutions. The trace element concentration was evaluated by ICP-OES. Furthermore, the CO2 emission was measured at the top of the leaching columns by capturing in NaOH solution and titration with HCl, in the presence of BaCl2. An increase in the pH of the leachate was observed for both neutralizing agents, with slightly higher values for steel slag. The EC was lower at the higher lime dose at an early stage of the experiment, and CO2 emission was greater with the use of limestone compared to steel slag. A decrease in trace element mobilization in the presence of both neutralizing agents was also observed. Therefore, the results showed that the use of steel slag is a suitable alternative to mitigate AMD, with the advantage of reducing CO2 emissions to the atmosphere compared to limestone.

Deicer Scaling Resistance of Concrete Mixtures Containing Slag Cement Phase 2: Evaluation of Different Laboratory Scaling Test Methods, TPF-5(100), 2012

With the use of supplementary cementing materials (SCMs) in concrete mixtures, salt scaling tests such as ASTM C672 have been found to be overly aggressive and do correlate well with field scaling performance. The reasons for this are thought to be because at high replacement levels, SCM mixtures can take longer to set and to develop their properties: neither of these factors is taken into account in the standard laboratory finishing and curing procedures. As a result, these variables were studied as well as a modified scaling test, based on the Quebec BNQ scaling test that had shown promise in other research. The experimental research focused on the evaluation of three scaling resistance tests, including the ASTM C672 test with normal curing as well as an accelerated curing regime used by VDOT for ASTM C1202 rapid chloride permeability tests and now included as an option in ASTM C1202. As well, several variations on the proposed draft ASTM WK9367 deicer scaling resistance test, based on the Quebec Ministry of Transportation BNQ test method, were evaluated for concretes containing varying amounts of slag cement. A total of 16 concrete mixtures were studied using both high alkali cement and low alkali cement, Grade 100 slag and Grade 120 slag with 0, 20, 35 and 50 percent slag replacement by mass of total cementing materials. Vinsol resin was used as the primary air entrainer and Micro Air® was used in two replicate mixes for comparison. Based on the results of this study, a draft alternative test method to ASTM C762 is proposed.

Letter health consultation : foundry slag used for road rock, Washington County, Iowa (2008)

A resident within one of the counties in your region has expressed some concern regarding potential adverse health effects from dust and material that may be found within foundry slag that has been used as a replacement for road rock. This consultation includes a comparison of nuisance issues from dust generated from a road constructed of foundry slag and dust generated from a road constructed from typical road rock. This consultation also includes a discussion of the potential health effects of exposure of heavy metals from incidental ingestion of foundry slag.

Yield and mineral nutrition of soybean, maize, and Congo signal grass as affected by limestone and slag

The objective of this work was to evaluate the efficiency of superficial application of limestone and slag, and their effects on soil chemical attributes and on yield and mineral nutrition of soybean, maize, and Congo signal grass (Urochloa ruziziensis). The experiment was carried out in a Rhodic Hapludox under no tillage system. The treatments consisted of the use of limestone or slag (silicates of calcium and magnesium) to correct soil acidity, and of a control treatment without the use of soil correctives. Rates were calculated in order to raise soil base saturation up to 70%. Soybean was sown in November 2006 and maize in December 2007. Congo signal grass was sown right after the harvests of soybean and maize, and it was cropped during the off-seasons. Soil chemical attributes were evaluated at 6, 12, and 18 months after the application of the corrective materials. Slag is an efficient source for soil acidity correction, being able to raise the exchangeable base levels in the soil profile faster than lime. Both limestone and slag increase dry matter yield of Congo signal grass, and grain yield of soybean and maize. Slag is more effective in improving maize grain yield.