Modelagem de dados de entrada para simulação estocástica de lavra

Mine simulation depends on data that is both coherent and representative of the mining operation. This paper describes a methodology for modeling operational data which has been developed for mine simulation. The methodology has been applied to a case study of an open-pit mine, where the cycle times of the truck fleet have been modeled for mine simulation purposes. The results obtained have shown that once the operational data has been treated using the proposed methodology, the system variables have proven to be adherent to theoretical distributions. The research indicated the need jar tracking the origin of data inconsistencies through the development of a process to manage inconsistent data from the mining operation.

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.

Briquetting of steel grit recovered from the ornamental rocks cutting waste

This paper presents the results obtained with the production of briquettes from the steel grit found in the residue of ornamental rocks. The grit recovered by magnetic separation was characterized by titrimetric analysis, EDS (Electron Dispersive Spectroscopy) and X-ray diffraction for the analysis of iron concentration in the residue. The size and distribution of particles were obtained by the granulometric analysis method and scanning electron microscopy (SEM). The process resulted in a concentrate containing 93% metallic iron. The maximum load before fracture of the green briquettes was 1.02kN and of the dry briquettes was 3.59kN.

Characterization and application of the solid waste generated in the production of calcium carbonate precipitate as a corrective for the soil acidity

The calcium carbonate industry generates solid waste products which, because of their high alkaline content (CaO, CaCO(3) and Ca (OH)(2)), have a substantial impact on the environment. The objectives of this study are to characterize and classify the solid waste products, which are generated during the hydration process of the calcium carbonate industry, according to ABNT`s NBR 10.000 series, and to determine the potential and efficiency of using these solid residues to correct soil acidity. Initially, the studied residue was submitted to gross mass, leaching, solubility, pH. X-ray Diffractometry, Inductive Coupled Plasma - Atomic Emission Spectrometry (ICP-AES), granularity and humidity analyses. The potential and efficiency of the residue for correcting soil acidity was determined by analysis of the quality attributes for soil correctives (PN, PRNT, Ca and Mg contents, granularity). Consequently, the results show that the studied residue may be used as a soil acidity corrective, considering that a typical corrective compound is recommended for each different type of soil. Additionally, the product must be further treated (dried and ground) to suit the specific requirements of the consumer market.

Assessment of the cavitation erosion resistance in high nitrogen austenitic stainless steels: study of the wear mechanisms

Specimens of a UNS S31803 steel were submitted to high temperature gas nitriding and then to vibratory pitting wear tests. Nitrided samples displayed fully austenitic microstructures and 0.9 wt. % nitrogen contents. Prior to pitting tests, sample texture was characterized by electron backscattering diffraction, EBSD. Later on, the samples were tested in a vibratory pit testing equipment using distilled water Pitting tests were periodically interrupted to evaluate mass loss and to characterize the surface wear by SEM observations. At earlier pit erosion, stages intense and highly heterogeneous plastic deformation inside individual grains was observed. Later on, after the incubation period, mass loss by debris detachment was observed. Initial debris micro fracturing was addressed to low cycle fatigue. Damage started at both sites, inside the grains and grain boundaries. The twin boundaries were the most prone to mass-loss incubation. Grains with (101) planes oriented near parallel to the sample surface displayed higher wear resistance than grains with other textures. This was attributed to lower resolved stresses for plastic deformation inside the grains with (101)

ASTM A923-Practice A application to identify intermetallic phases in a UNS S32750 superduplex welded joint

Duplex and superduplex stainless steels present superior mechanical and corrosion properties when compared to usual stainless steels. This superiority is based on chemical composition when in a balanced microstructure (approximately 50% of ferrite). During welding, changes may occur in both, the chemical composition and volume fraction of phases in the material, which may generate the presence of intermetallic phases and, as a consequence, modify the mechanical and corrosion properties of this group of stainless steels. The objective of this work is to apply ASTM A923- Practice A to verify the presence of intermetallic phases in welded joints of UNS 32750 su-perduplex stainless steel. Tubes of UNS 32750, with external diameters of 18 and 44 mm and a thickness of 1.5 mm, were welded using orbital GTAW, with filler metal 25Cr-10Ni-4Mo and a diameter of 0.8 mm. The metal-based and welded joints were characterized by optical and scanning electron microscopy. The results showed that there was no precipitation of the intermetallic phase, such as sigma phase, detected by ASTM A923, but the HAZ of the two tubes studied presented small regions with chromium nitrides, which can also change the properties of welded joins.

Life cycle assessment and life cycle cost of sugar plants evaporators

The evaporators of sugar plants in Brazil have used carbon steel intensively because of it is, a low priced material, which possesses inferior corrosion resistance. The materials more indicated for the substitution of carbon steel are stainless steels, however they are considered expensive. The environmental and financial performances of evaporator pipes constructed with carbon steel and with types AISI 304 444 and 439 stainless steel were evaluated. For the environmental evaluation, the Life Cycle Assessment (LCA) methodology Was used and it, revealed that stainless steel is more environmentally efficient than carbon steel. The life cycle costing (LCC) technique was the tool chosen for the financial evaluation and it showed that stainless steel is a better investment option compared to carbon steel. The results also indicate that LCA and LCC methodologies must be used together Therefore, it can he seen that safer environmental products can come to be the most profitable investment options.

Deterministic mathematical model for the prediction of the as-cast macrostructure

A multiphase deterministic mathematical model was implemented to predict the formation of the grain macrostructure during unidirectional solidification. The model consists of macroscopic equations of energy, mass, and species conservation coupled with dendritic growth models. A grain nucleation model based on a Gaussian distribution of nucleation undercoolings was also adopted. At some solidification conditions, the cooling curves calculated with the model showed oscillations (""wiggles""), which prevented the correct prediction of the average grain size along the structure. Numerous simulations were carried out at nucleation conditions where the oscillations are absent, enabling an assessment of the effect of the heat transfer coefficient on the average grain size and columnar-to-equiaxed transition.

The importance of the industrialization of Brazilian shale when faced with the world energy scenario

This article discusses the importance of the industrialization of Brazilian shale based on factors such as: security of the national energy system security, global oil geopoliticsl, resources available, production costs, oil prices, environmental impacts and the national oil reserves. The study shows that the industrialization of shale always arises when issues such as peak oil or its geopolitics appear as factors that raise the price of oil to unrealistic levels. The article concludes that in the Brazilian case, shale oil may be classified as a strategic resource, economically viable, currently in development by the success of the retorting technology for extraction of shale oil and the price of crude oil. The article presents the conclusion that shale may be the driving factor for the formation of a technology park in Sao Mateus do Sul, due to the city`s economic dependence on Petrosix.

Análise econômica comparativa de empresas de água mineral quanto ao porte

This work makes a comparative economic analysis of a small-, medium- and large-sized mineral water company, the three of which are localized in the State of Sao Paulo. All have the same lines of production such as glasses, bottles and big bottles. The analysis involves the cash flow comparison of the three companies.

Structure and properties of an austenitic stainless steel AISI 316L grade ASTM F138 after low temperature plasma nitriding

Austenitic stainless steels cannot be conventionally nitrided at temperatures near 550 degrees C due to the intense precipitation of chromium nitrides in the diffusion zone. The precipitation of chro-mium nitrides increases the hardness but severely impairs corrosion resistance. Plasma nitriding allows introducing nitrogen in the steel at temperatures below 450 degrees C, forming pre-dominantly expanded austenite (gamma(N)), with a crystalline structure best represented by a special triclin-ic lattice, with a very high nitrogen atomic concentration promoting high compressive residual stresses at the surface, increasing substrate hardness from 4 GPa up to 14 GPa on the nitrided case.

Technological characterization of phosphate ore types from the Salitre Alkaline Complex, MG - Fosfertil Area

The present study was carried out on six different ore types from the Salitre Alkaline Complex aiming to determine their mineralogical composition and the major features that are relevant in the mineral processing. The P(2)O(5) grades vary from 9 to 25%. The slime content (-0, 020 mm) varies between 20 and 34% (w/w) and carries 17-22% of the P(2)O(5) content. The samples essentially consist of apatite, iron oxi-hydroxides, ilmenite, clay minerals, carbonate, quartz, pyroxene, perovskite, secondary phosphates and other minor accessory minerals. Below 0.21 mm, apatite essentially occurs in free particles showing a clean surface or a weak coating of it-on oxi-hydroxides; the highly covered apatite (not recoverable by flotation) varies from 6 to 9%. In the deslimed fraction (above 0.020 mm) more than 97% of the total phosphor content occurs as apatite; the estimated P 2 0 5 potential recovery in flotation concentration is over 90% (71-76% overall recovery).

LPS Removal from an E. Coli Fermentation Broth Using Aqueous Two-Phase Micellar System

In biotechnology, endotoxin (LPS) removal from recombinant proteins is a critical and challenging step in the preparation of injectable therapeutics, as endotoxin is a natural component of bacterial expression systems widely used to manufacture therapeutic proteins. The viability of large-scale industrial production of recombinant biomolecules of pharmaceutical interest significantly depends on the separation and purification techniques used. The aim of this work was to evaluate the use of aqueous two-phase micellar system (ATPMS) for endotoxin removal from preparations containing recombinant proteins of pharmaceutical interest, such as green fluorescent protein (GFPuv). Partition assays were carried out initially using pure LPS, and afterwards in the presence of E. coli cell lysate. The ATPMS technology proved to be effective in GFPuv recovery, preferentially into the micelle-poor phase (K(GFPuv) < 1.00), and LPS removal into the micelle-rich phase (%REM(LPS) > 98.00%). Therefore, this system can be exploited as the first step for purification in biotechnology processes for removal of higher LPS concentrations. (C) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 26: 1644-1653, 2010

Low-Level Laser Therapy in Chronic Autoimmune Thyroiditis: A Pilot Study

Background and Objectives: Chronic autoimmune thyroiditis (CAT) remains the most common cause of acquired hypothyroidism There is currently no therapy that is capable of regenerating CAT-damaged thyroid tissue The objective of this study was to gauge the value of applying low-level laser therapy (LLLT) in CAT patients based on both ultrasound studies (USs) and evaluations of thyroid function and thyroid autoantibodies. Study Design/Materials and Methods: Fifteen patients who had hypothyroidism caused by CAT and were undergoing levothyroxine (LT4) treatment were selected to participate in the study Patients received 10 applications of LLLT (830 nm, output power 50 mW) in continuous mode, twice a week, using either the punctual technique (8 patients) or the sweep technique (7 patients), with fluence in the range of 38-108 J/cm(2) USs were performed prior to and 30 days after LLLT USs included a quantitative analysis of echogenicity through a gray-scale computerized histogram index (El). Following the second ultrasound (30 days after LLLT), LT4 was discontinued in all patients and, if required, reintroduced Truodothyronine, thyroxine (T4), free T4, thyrotropin, thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) antibodies levels were assessed before LLLT and then 1, 2, 3, 6, and 9 months after LT4 withdrawal. Results: We noted all patients` reduced LT4 dosage needs, including 7 (47%) who did not require any LT4 through the 9-month follow-up The LT4 dosage used pre-LLLT (96 +/- 22 mu g/day) decreased in the 9th month of follow-up (38 23 mu g/day; P<0.0001) TPOAb levels also decreased (pre-LLLT = 982 +/- 530 U/ml, post-LLLT = 579 454 U/ml, P = 0 016) TgAb levels were not reduced, though we did observe a post-LLLT increase in the EI (pre-LLLT = 0 99 +/- 0.09, post-LLLT= 1.21 +/- 0.19, P=0.001) Conclusion: The preliminary results indicate that LLLT promotes the improvement of thyroid function, as patients experienced a decreased need for LT4, a reduction in TPOAb levels, and an increase in parenchymal echogenicity Lasers Surg. Med. 42:589-596, 2010. (C) 2010 Wiley-Liss, Inc

Development of Lifetime Comorbidity in the World Health Organization World Mental Health Surveys

Context: Although numerous studies have examined the role of latent variables in the structure of comorbidity among mental disorders, none has examined their role in the development of comorbidity. Objective: To study the role of latent variables in the development of comorbidity among 18 lifetime DSM-IV disorders in the World Health Organization World Mental Health Surveys. Design: Nationally or regionally representative community surveys. Setting: Fourteen countries. Participants: A total of 21 229 survey respondents. Main Outcome Measures: First onset of 18 lifetime DSM-IV anxiety, mood, behavior, and substance disorders assessed retrospectively in the World Health Organization Composite International Diagnostic Interview. Results: Separate internalizing (anxiety and mood disorders) and externalizing (behavior and substance disorders) factors were found in exploratory factor analysis of lifetime disorders. Consistently significant positive time-lagged associations were found in survival analyses for virtually all temporally primary lifetime disorders predicting subsequent onset of other disorders. Within-domain (ie, internalizing or externalizing) associations were generally stronger than between-domain associations. Most time-lagged associations were explained by a model that assumed the existence of mediating latent internalizing and externalizing variables. Specific phobia and obsessive-compulsive disorder (internalizing) and hyperactivity and oppositional defiant disorders (externalizing) were the most important predictors. A small number of residual associations remained significant after controlling the latent variables. Conclusions: The good fit of the latent variable model suggests that common causal pathways account for most of the comorbidity among the disorders considered herein. These common pathways should be the focus of future research on the development of comorbidity, although several important pairwise associations that cannot be accounted for by latent variables also exist that warrant further focused study.