Doctor of Philosophy / Agronomy / DeAnn R. Presley / Crop residue removal for livestock feeding and biofuel production at large scales must be evaluated to assess impacts on soil productivity and properties. Among all the potential negative impacts, wind erosion is a major concern in the central Great Plains. We conducted an on-farm study from 2011 to 2013 by removing crop residue at five levels (0, 25, 50, 75, and 100%) to determine the effects of crop residue removal on soil wind erosion parameters such as dry aggregate size distribution including soil wind erodible fraction (EF <0.84 mm aggregates), geometric mean diameter (GMD) and geometric standard deviation (GSD), dry aggregate stability, and soil surface roughness. The sub-model of Wind Erosion Prediction System (WEPS) developed by the USDA-ARS, Single-event Wind Erosion Evaluation Program (SWEEP) is a stand-alone companion software package that can be applied to simulate soil loss and dust emission from a single windstorm event. We applied measured data (i.e. EF, GMD, GSD, and roughness) to SWEEP for predicting wind velocity that can initiate wind erosion and soil loss under each crop residue removal condition with wind velocity at 13 m sˉ¹. The threshold wind velocity to initiate wind erosion generally decreased with increase in crop residue removal levels, particularly for residue removal >75%. The total amount of soil loss in 3 hours ranged from about 0.2 to 2.5 kg mˉ² and depends on soil condition and crop residue cover. On the other hand, high-yielding crops can produce abundant crop residue, which then raises the question that if a farmer wants to reduce residue, what could they do without removing it? The application of fertilizer on crop residue to stimulate microbial activity and subsequent decomposition of the residue is often debated. We conducted wheat straw decomposition field experiments under different fertilizer rates and combinations at three locations in western Kansas following wheat harvest in 2011 and 2012. A double shear box apparatus instrumented with a load cell measured the shear stress required to cut wheat straw and photomicrography was used to measure the cross-sectional area of wheat straw after shearing. Total C and N were also analyzed. The fertilizer rate and timing of application during summer 2012 and Fall 2013 at the Hays site had impacts on wheat straw shear stress at break point. Across site years, earlier (fall) fertilizer application generally resulted in lower remaining aboveground biomass as compared to a spring application. Multivariate and linear regressions suggested that N and C:N ratio partially explain the results observed with respect to treatment effects on winter wheat residue decomposition.

The communicative interaction between contractor and subcontractor of residue forwarder plays a crucial role in the efficiency of handling forest residue. Since that type of work is at the end of the harvesting process, it may be that it is not as prioritized as the previous harvesting measures. The study investigates the communicative interaction between subcontractor that drives a residue forwarder and contractor and its connection to work-related production stops. The study was accomplished by a web-based survey and quantitative interviews conducted with eight selectively selected residue forwarder drivers in southern Sweden. The result of the survey showed that the average of all total production stops was one hour and 52 minutes under an average stop period of 25 working days. Most of the stops were caused by other work-related problems. Communication problems accounted for 20% of the number of production stops and the average stop duration was one hour and five minutes. The time when a residue forwarder was inactive seventeen minutes per day. In conclusion, the communicative problems are not the main reason to inactivity for residue forwarders. However, communication plays an important role in productive harvesting and represent the biggest possibility for improvement in the communication between residue forwarder drivers and contractor, which could lead to fewer production stops.     Residue Forwarders, Communication Problems, Production Stop and Forest residue. / Det kommunikativa samspelet mellan uppdragsgivare och risskotarförare kan vara ett led i effektiviteten vid hanteringen av GROT, vilket är en förkortning för grenar och toppar. I och med att arbetet infaller sist i avverkningsledet kan det vara lägre prioriterat än de tidigare avverkningsåtgärderna. Studien undersöker det kommunikativa samspelet mellan risskotarförare och uppdragsgivare och dess anknytning till arbetsrelaterade produktionsstopp. Det gjordes med hjälp av en webbaserad enkät ochkvantitativa intervjuer som genomfördes av åtta selektivt utvalda risskotarförare i södra Sverige. Resultatet från den webbaserade enkätundersökningen visar att medelvärdet av alla sammanlagda produktionsstopp var en timme och 52 minuter under en medelvärdesperiod av 25 arbetsdagar. Störst andel stopp orsakas av övriga problem. Kommunikationsproblem stod för 20 % av antalet produktionsstopp och medelvärdet av stoppens längd var en timme och fem minuter. Tiden då en risskotare står stilla under en arbetsdag uppgick till sjutton minuter. Sammanfattningsvis kan det klargöras att de kommunikativa problemen inte är den största orsaken till att risskotare står stilla. Dock spelar kommunikationen en viktig roll för ett produktivt avverkningsarbete. Slutligen finns det förbättringsmöjligheter i kommunikationen mellan risskotarförare och uppdragsgivare vilket skulle kunna leda till färre produktionsstopp.   Risskotare, Kommunikationsproblem, Produktionsstopp och GROT.

Um dos problemas ambientais das cidades contemporâneas é a geração excessiva de resíduos sólidos urbanos (RSU), tais como os restos orgânicos, as embalagens que envolvem os produtos, pneus, garrafas, latas de refrigerante, papel, entre outros resíduos. A crescente quantidade de resíduos gerados nas diversas atividades humanas, residências, comércio, serviços e na manutenção das cidades, tem sido causada pelo modelo atual de desenvolvimento econômico, pelo crescimento acelerado da população, sua concentração em cidades e na mudança de padrão de consumo ocorrida nas últimas décadas. A gestão inadequada desses resíduos tem causado impactos negativos ao meio ambiente, porque causa danos desastrosos ao solo, ao ar e às águas superficiais carreando agentes poluentes presentes nesses resíduos, os quais infiltram no solo e podem atingir as águas subterrâneas. Neste contexto, o presente trabalho teve por objetivo avaliar a gestão dos resíduos sólidos urbanos gerados no Município de Coronel Fabriciano, localizado na Região do Vale do Aço do Estado de Minas Gerais, através de análise da situação encontrada e a trajetória municipal do inicio desta pesquisa em setembro de 2004 a dezembro de 2006. Para tal, foi elaborado e utilizado como instrumento de trabalho, o Diagnóstico Situacional de RSU para a coleta de dados da situação da Gestão Urbana Municipal, análise dos Serviços de Limpeza Urbana prestado pela Secretaria Municipal de Obras e Serviços Urbanos e, também, pelas empresas prestadoras de serviços, contratadas por essa Prefeitura e avaliação gravimétrica destes RSU. Foi escolhido este instrumento por constituir-se em uma avaliação e planejamento que objetiva direcionar as ações a serem realizadas pelo poder público e assim definir a importância e posteriormente prevenir, ou mesmo reduzir, os efeitos gerados ao meio ambiente em decorrência de falha na gestão municipal. Os resultados ambientais foram mensurados tendo como princípio norteador a Gestão de RSU, considerando alternativas de viabilidade política, econômico-financeira e institucional-administrativa e por fim, apresentar uma proposta de Política de Gestão de RSU, tendo como instrumento o Plano de Gerenciamento Integrado de Resíduos Sólidos Urbanos (PGIRSU), que busca a preservação da saúde pública, proteção e melhoria da qualidade do meio ambiente, recuperação de áreas degradada e assegurando a utilização adequada e racional dos recursos naturais para a área de deposição final a ser construída. Foram identificados avanços na gestão de RSU em Coronel Fabriciano, contudo ainda muito se tem o que fazer nessa área, objetivando minimizar os impactos negativos causados, como também atores sociais que têm cooperado com algumas das ações do poder público municipal na gestão dos RSU e atuam junto à Secretaria Municipal de Obras e Serviços Urbanos e à Secretaria Municipal de Assistência Social, a exemplo do Centro Universitário do Leste de Minas Gerais (UNILESTE-MG), responsável pelo projeto extensionista de Educação Ambiental. / One of the environment issues of contemporary residues is the over generation of solid urban residues (SUR), like organic remains, the packing around the products, tires, bottle, soft drink cans, paper and other residues. The increasing amount of residues produced in many human activities, residences, commerce, services and in the maintenance of the cities, has been caused by the current model of economical development, by the fast population growth, its concentration inside the cities and in the consumption pattern change occurred in the last decades. The inadequate management of these residues has caused negative impact in the environment because it causes outrageous damage to the soil, air and to the superficial water, carrying polluting agents present in these residues, which permeate the soil and can reach the underground waters. Therefore, the current study had as a goal, to evaluate the management of solid urban residues produced in Coronel Fabriciano Town, located in the Region of Vale do Aço in Minas Gerais State, through the analysis of the situation found and the municipal path from the beginning of this research in September 2004 to December 2006. To have it done, a Situational Diagnosis of SUR was elaborated and used as work tool for the data collecting of the Urban Municipal Management, of the Urban Cleaning Services analysis done by the Building and Urban Service Municipal General Office and also by the installment service companies, contracted by the City Hall and gravimetric evaluation of these SUR. This tool was chosen because for been in an evaluation and planning that aim to direct the actions to be done by the public authority, then define the importance and after all prevent or even reduce the effects to the environment due to the lack of municipal management. The environmental results were measured having as a guidance principle the SUR management, considering choices of political’s, economic-financial’s and institutional-administrative’s viability and finally, to present a SUR Management Politics offer, having the Integrated Management of Solid Urban Residue Plan (IMSURP) as a tool that looks up to the public health preservation, protection and improvement of the environment’s quality, recuperation of the degraded areas and guaranteeing the appropriated and rationalized using of the natural resources to the area of final deposition to be built. Advances in the SUR Management in Coronel Fabriciano were identified but there is a lot to be done in this area, aiming to minimize the negative impacts caused and the social agents as well who have cooperated with some of the actions of the municipal public authority in the SUR management and acted together with the Building and Urban Service Municipal General Office, like Centro Universitário do Leste de Minas Gerais (UNILESTE-MG), responsible for the extension project of Environmental Education.

In this paper, we provide a generalization of binary quadratic residue codes to the cases of higher power prime residues over the finite field of the same order, which we will call qth power residue codes. We find generating polynomials for such codes, define a new notion corresponding to the binary concept of an idempotent, and use this to find square root lower bound for the codeword weight of the duals of such codes, which leads to a lower bound on the weight of the codewords themselves. In addition, we construct a family of asymptotically bad qth power residue codes. / text

La décomposition des résidus végétaux joue un rôle essentiel dans le cycle biogéochimique des éléments nutritifs et influence le fonctionnement des écosystèmes. La composition biochimique intrinsèque des résidus végétaux est un facteur clé qui influe sur les processus de décomposition dans le sol tandis que la majorité des réactions biochimiques dans le sol, liées à la biodégradation des résidus végétaux, sont catalysées par des enzymes extracellulaires produites par les microorganismes. L'objectif global de cette étude était d'acquérir des connaissances fondamentales concernant l'impact de la qualité des résidus sur les fonctions microbiennes du sol et les modes d'intervention des enzymes du sol interviennent dans la décomposition des résidus végétaux. Cet objectif a été atteint en trois parties visant à : 1) déterminer le rôle des communautés initiales des résidus i.e. les microorganismes et leurs enzymes provenant des compartiments épiphytes et endophytes, et l'effet de la qualité des résidus végétaux sur les cinétiques des enzymes extracellulaires au cours du processus de décomposition dans le sol 2) étudier l'effet des fonctions microbiennes du sol (biomasse microbienne et enzymes extracellulaires) liées à la minéralisation sur la décomposition ultérieure de résidus introduits dans le même sol 3) explorer les interactions entre la disponibilité en azote et la décomposition des composés phénoliques par l'action des activités oxydo-réductases, et développer une méthode pour mesurer ces activités dans des sols contrastés en utilisant un seul substrat. L'approche générale de cette étude a été de sélectionner les résidus végétaux de qualité chimique variable pour obtenir des cinétiques contrastées de minéralisation du C. Le maïs (Zea mays L.) a été choisi comme plante modèle en raison de variations chimiques et structurales (Mexxal, F2, F2bm1, F292bm3) des parties aériennes (feuilles, entre-nœuds) et souterraines (racines). Des tiges de lin marqué au 13C ont été utilisées pour quantifier avec précision la minéralisation du carbone dans les différents réservoirs de carbone. Afin d'évaluer les relations entre la qualité des résidus végétaux et les fonctions biologiques associées au sol, des expériences en microcosmes contrôlés ont été réalisées en utilisant des sols agricoles et forestiers. La minéralisation du carbone, les caractéristiques chimiques des résidus (teneurs en C et N, les sucres totaux et lignine), la biomasse microbienne et les activités enzymatiques (L-leucine aminopeptidase (LAP), cellobiohydrolase (CBH-1), xylanase, cellulase et la laccase) ont été déterminées à différents stades de décomposition. Les résultats de la première étude ont indiqué que les activités de micro-organismes épiphytes et endogènes étaient du même ordre de grandeur dans le cas des racines, tandis que les activités des enzymes spécifiques (cellulase, xylanase et laccase) étaient fortement corrélées à la dégradation de leurs substrats cibles (glucanes, xylanes et lignine, respectivement). Dans la seconde étude, l'addition répétée de résidus a eu peu d'effet sur la biomasse microbienne et la dynamique enzymatique, sauf la LAP et la laccase. Ces résultats suggèrent que la qualité des résidus végétaux est le principal facteur déterminant les modes d'action de la biomasse microbienne et de leurs enzymes extracellulaires durant le processus de décomposition dans le sol. Les résultats de la dernière étude ont démontré que l'addition d'azote réprimait la minéralisation du carbone des résidus les moins lignifiés (F2, F2bm1), mais n'a pas affecté celle du résidu plus lignifié (F292bm3) au cours de la décomposition à long terme. L'ABTS est apparu comme un meilleur substrat que le L-DOPA, le pyrogallol et le TMB pour estimer les activités phénoloxydase et peroxydase.Mots clés: décomposition, biomasse microbienne, enzymes extracellulaires, qualité des résidus, maïs. / Plant residue decomposition plays a pivotal role in the biogeochemical cycling of nutrients and influences ecosystem functioning. The intrinsic biochemical composition of plant residues is a key factor influencing decomposition processes in soil while the majority of biochemical reactions in soil, related to the biodegradation of plant residues, are catalyzed by extracellular enzymes produced by microorganisms. The overall goal of this research study was to gain fundamental knowledge regarding the impact of residue quality on soil microbial functions and the principles by which soil enzymes mediate plant residue decomposition. This goal was achieved in three parts: 1) to determine the role of the initial residue community i.e. microorganisms and enzymes from the epiphytic and endophytic compartments and effect of plant residue quality on the extracellular enzyme kinetics during the decomposition process in soil 2) to investigate the effect of soil microbial functions (microbial biomass and extracellular enzymes) on the subsequent residue decomposition in the same soil 3) to explore the interactions between nitrogen availability and the decomposition of phenolic compounds through the action of oxydo-reductase enzymes activities and to develop a method to measure these activities in contrasted soils using a single substrate. The general approach of this study was to select plant residues with variations in their chemical quality to obtain contrasted C mineralization kinetics. Maize (Zea mays L.) was selected as a model plant because of variations in chemical and structural characteristics (Mexxal, F2, F2bm1, F292bm3) of aerial (leaves, internodes) and underground parts (roots). 13C-labeled flax stems were used to quantify accurately carbon mineralization in different carbon pools. To assess the relationships between plant residue quality and associated soil biological functions, controlled microcosm experiments were performed using agricultural and forest soils. Carbon mineralization and chemical characteristics (C and N contents, total sugars and lignin contents) of the plant residue, microbial biomass and enzyme activities (L-leucine aminopeptidase (LAP), cellobiohydrolase (CBH-1), xylanase, cellulase and laccase) were determined at different stages of decomposition. The results of first study indicated that activities of epiphytic and endogenic microorganisms were of the same order of magnitude in case of roots while the activities of specific enzymes (cellulase, xylanase and laccase) were highly correlated to the degradation of their target substrates (glucans, xylans and lignin, respectively). In the second study, little effect of repeated residue addition was observed on microbial biomass and enzyme dynamics except LAP and laccase. These results suggest that plant residue quality is the main factor which determines the fate/patterns of microbial biomass and their extracellular enzymes during decomposition process in soil. The results of last study demonstrated that nitrogen addition repressed the carbon mineralization of less lignified residues (F2, F2bm1) but did not affect more lignified residue (F292bm3) in long term decomposition. For estimation of phenol oxidase and peroxidase activities, ABTS appeared as a better substrate than L-DOPA, pyrogallol and TMB.Key words: decomposition, microbial biomass, extracellular enzymes, residue quality, maize.

Amino acid frequencies in proteins may not be at equilibrium. We consider two possible explanations for the nonzero net residue fluxes in drosophilid proteins. First, protein interiors may have a suboptimal residue composition and be under a selective pressure favoring stability, that is, leading to the loss of polar (and the gain of large) amino acids. One would then expect stronger net fluxes on the protein interior than at the exposed sites. Alternatively, ifmost of the polarity loss occurs at the exposed sites and the selective constraint on amino acid composition at such sites decreases over time, net loss of polarity may be neutral and caused by disproportionally high occurrence of polar residues at exposed, least constrained sites.We estimated net evolutionary fluxes of residue polarity and volume at sites with different solvent accessibility in conserved protein families from 12 species of Drosophila. Net loss of polarity, miniscule in magnitude, but consistent across all lineages, occurred at all sites except the most exposed ones, where net flux of polaritywas close to zero or, in membrane proteins, even positive. At the intermediate solvent accessibility the net fluxes of polarity and volumewere similar to neutral predictions, whereas much of the polarity loss not attributable to neutral expectations occurred at the buried sites. These observations are consistent with the hypothesis that residue composition in many proteins is structurally suboptimal and continues to evolve toward lower polarity in the protein interior, in particular in proteins with intracellular localization. The magnitude of polarity and volume changes was independent from the protein's evolutionary age, indicating that the approach to equilibrium has been slow or that no such single equilibrium exists.

A statewide mail survey of primary and secondary wood product manufacturers was undertaken to quantify the production and consumption of wood residues in Virginia. Two hundred and sixty-six wood product manufacturers responded to the study and they provided information on the production, consumption, markets, income or disposal costs, and disposal methods of wood residues. Hardwood and pine sawmills produce approximately 66 percent of Virginia's wood residues. Virginia's wood product manufacturers produce three primary residues: chips, bark, and sawdust. These three residues comprised nearly 83 percent of Virginia's total residue production in 1996. Approximately 200,000 tons or 6 percent of Virginia's wood residues appear not to have adequate markets. A second survey was directed to all municipal waste, construction and demolition, and "other" waste facilities in Virginia. The focus of this survey was to quantify the volume of solid wood residues received at the facilities. In addition, the study was conducted to ascertain tipping fees, did the landfill(s) actively market wood residues, were wood residues recycled, were wood residues restricted from being landfilled, and disposal methods for wood residues. Additionally, the survey was conducted to determine the type of waste facility operated, the quantity of all wastes directed to each landfill, and tipping fees. Seventy-five respondents provided information on the total and solid wood waste volumes received at their respective facilities, recycling efforts, and disposal practices. Approximately 689,000 tons of solid wood, or 8 percent of all wastes, was received at Virginia's landfills in 1996. Virginia's waste facilities reported processing or recycling approximately 406,000 tons or 59 percent of the solid wood received in 1996. / Master of Science

Gunshot residue (GSR) analysis is a crucial aspect of the investigation of firearms-related incidents. The presence of GSR on a person or surface can provide valuable insight regarding proximity or involvement of an individual in a shooting incident. Traditionally, GSR analysis relies on the detection of inorganic compounds within the ammunition, known as inorganic gunshot residue (IGSR). These inorganic compounds are comprised of lead, barium, and antimony. IGSR compounds originate from the content of the primer, and each individual element is expelled during discharge, fused while molten, and land on nearby surfaces. Stubs with an adhesive coat are used to collect these particles by pressing against a surface suspected to have GSR particles. The current analytical method for detection and identification of IGSR, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM/EDS), surveys GSR stubs for both the elemental composition as well as the morphology of the compounds. Positive identification requires both the elemental composition and spherical morphology of IGSR. Several issues exist with the nature of IGSR as well as the current method of analysis. Identification by SEM/EDS not only requires time for transportation and labor but may also produce false negatives due to inconsistent shape or lack of all three elements. The development of a rapid and robust analytical technique would address these deficiencies. Mass spectrometry (MS) is a standard analytical technique known for its specificity and accuracy. New advancements in research and technology have produced the ability to miniaturize MS while retaining its superior capabilities in identification. The characteristics of IGSR also pose issues in terms of validity, such as specificity to discharging a weapon, and ability to be transferred or wiped off. Qualities such as these can lead to both false negatives and false positives. In recent years, advances in forensic science research have studied the composition of organic gunshot residue (OGSR) as well as new methods for detecting these compounds. Research has pointed towards advantages in OGSR that would rectify the analytical issues seen in using IGSR as the target compound. Some qualities of OGSR that would improve GSR detection are its specificity to GSR, the molecular complexity of its components, its higher persistence on surfaces, and lower transferability. This study addressed both issues by employing the MX908 High Pressure Mass Spectrometer and developing an analytical method for major OGSR targets. The objective of this research was to test the MX908’s ability to ionize and detect Nitroglycerin (NG), Diphenylamine (DPA), Ethyl Centralite (EC), Dibutyl Phthalate (DBP), and Nitroguanidine (NQ). Furthermore, these experiments tested a range of voltage parameters to achieve optimal fragmentation, and ultimately an accurate and specific analytical method.

Four studies were conducted to evaluate the potential for post-extraction algal residue (PEAR) to be incorporated as a protein source in the grazing sector of the beef cattle industry. In Experiment 1, blends of PEAR and conventional protein supplements (dried distillers’ grains, DDG; cottonseed meal, CSM) were offered to steers consuming Bermudagrass to evaluate palatability of PEAR. Supplement completion, time required for consumption, and amount of supplement consumed were recorded. In Experiment 2, isonitrogenous amounts of PEAR and CSM (100 mg N/kg BW) were supplemented to steers consuming low-quality forage to compare effects on nutrient utilization. Experiment 3 evaluated the optimal inclusion rate of PEAR to steers consuming low-quality forage. Treatments included no supplemental protein, 3 levels of PEAR (50, 100, and 150 mg N/kg BW) and 1 level of CSM (100 mg N/kg BW). In Experiment 4, the effects of upstream operations on the nutritive value of PEAR were quantified. Observations indicate PEAR may be blended with existing protein sources in the beef industry without negatively affecting palatability, but there may be palatability concerns when PEAR is offered alone. Provision of 100 mg N/kg BW of PEAR or CSM stimulated forage intake (P ≤ 0.05) and increased N retention (P = 0.02) relative to unsupplemented animals. Imbalances in mineral intakes (Ca:P ratio of 8:1) were observed when PEAR was supplemented, but not CSM. Total digestible OM intake (TDOMI) responded quadratically (P = 0.01) to increasing provision of PEAR with maximization occurring when PEAR was provided at 100 mg N/kg BW. There was not a difference in TDOMI (P = 0.13) at isonitrogenous levels of PEAR and CSM, indicating forage utilization was stimulated to a similar extent. Excess mineral levels and imbalances in PEAR were largely a result of cultivation, harvesting, and extraction procedures which could be controlled. Thus, there is potential to alter production streams to optimize oil yield and co-product value. Overall, our results indicate PEAR can be incorporated as a protein source in the beef cattle industry, thus increasing economic viability of biofuel production from algal biomass.

O resíduo niquelífero, objeto deste estudo, foi gerado pelo processo de extração piro-hidrometalúrgico, constituindo um problema para sua destinação. Este trabalho pretende contribuir com os conhecimentos sobre o processo de recuperação de metais de interesse por redução carbotérmica na forma de pelotas auto-redutoras. O estudo envolveu a caracterização das matérias-primas, mostrando que 75 a 80% de níquel encontra-se na forma de silicatos de magnésio e de ferro, e que a concentração física do resíduo não é possível. O trabalho apresenta os fundamentos da redução carbotérmica e uma revisão dos processos de extração de níquel, com ênfase nos resíduos gerados e sua utilização. Foram fabricados quatro tipos de pelotas auto-redutoras contendo resíduo niquelífero, empregando-se coque de petróleo como seu redutor. As variáveis estudadas foram o tempo e a temperatura de redução, a quantidade de redutor e a adição de cal. As pelotas foram ensaiadas em um equipamento termogravimétrico para a determinação da perda de peso e parâmetros cinéticos, as temperaturas entre 1273 K e 1573 K. As amostras ensaiadas foram analisadas por microscopia eletrônica de varredura, análise de porosidade e análise de imagens. Os resultados mostram que a redução das pelotas auto-redutoras com 8% ou 12% de coque, abaixo de 1473 K, não sofre influência quanto à quantidade de redutor. Nas temperaturas superiores a 1473 K observou-se uma maior redução na pelota com 12% de coque, sob as mesmas condições experimentais. As análises de imagens e as medidas de porosidade indicaram que para os dois tipos de pelota, com 8% ou 12% de coque, a porosidade diminui com o aumento do tempo de redução para uma mesma temperatura. Para um mesmo tempo de redução, com o aumento da temperatura, a diminuição da porosidade é maior.Independentemente do tipo de pelota, da temperatura e do tempo, observou-se que o composto silicatado com alto conteúdo de magnésio dificulta a redução de metais presentes nela. Os resultados obtidos mostram que, nas condições estudadas, não é possível a redução total dos elementos ferro, níquel e cobalto que, permanecem parcialmente na fase não metálica. A fração de reação máxima atingida a 1573 K, durante 45 minutos, pela pelota com 12% de coque, foi de aproximadamente 73%. / The nickeliferous residue, object of this work, was produced by a piro-hydrometallurgical extraction process, constituting a problem for its destination. Such work aims at extending the knowledge of recovery processes of desired metal values by carbothermal reduction in the form of self-reduction pellets. The present study involved the description of raw materials, demonstrating that 75% to 80% of nickel is found in the form of magnesium and iron silicates, besides showing that it is not possible to obtain any physical concentration of such residue. This work introduces the basics of carbothermal reduction and a review of nickel extraction processes, highlighting the residues generated and their use. Four different types of self-reduction pellets were produced, containing nickeliferous residue and employing petroleum coke as its reductant. The variables of this study were time and temperature of reduction, the quantity of reductant and the amount of lime added. The pellets were employed in an experiment using a thermogravimetric instrument for determining the weight loss and kinetics parameters at temperatures between 1273 K and 1573 K. Samples were examined through scanning electronic microscopy, porosity and image analyses. Results show that the reduction of 8% and 12% self-reduction pellets, below 1473 K, is not influenced by the quantity of reductant. A stronger reduction has been observed in 12% of coke at temperatures above 1473 K, under similar experimental conditions. Image analyses and measures of porosity indicated that for both pellets, 8% and 12%, porosity reduced after an increase in reduction\'s time at the same temperature. The decrease in porosity is higher as temperature rises at a similar reduction time.Irrespective of the time, temperature and the pellet\'s nature, it has been noted that the silicate compound with high magnesium content makes it difficult for metals presented in the pellet to suffer reduction. Results demonstrate that under our experimental conditions iron, nickel and cobalt cannot be totally reduced, remaining partly in their non-metallic stage. The fraction of maximum reaction reached by 12% of coke pellet, at 1573 K, during 45 minutes, was of approximately 73%.