Improving the competitiveness of electrolytic Zinc process by chemical reaction engineering approach

This doctoral thesis describes the development work performed on the leachand purification sections in the electrolytic zinc plant in Kokkola to increase the efficiency in these two stages, and thus the competitiveness of the plant. Since metallic zinc is a typical bulk product, the improvement of the competitiveness of a plant was mostly an issue of decreasing unit costs. The problems in the leaching were low recovery of valuable metals from raw materials, and that the available technology offered complicated and expensive processes to overcome this problem. In the purification, the main problem was consumption of zinc powder - up to four to six times the stoichiometric demand. This reduced the capacity of the plant as this zinc is re-circulated through the electrolysis, which is the absolute bottleneck in a zinc plant. Low selectivity gave low-grade and low-value precipitates for further processing to metallic copper, cadmium, cobalt and nickel. Knowledge of the underlying chemistry was poor and process interruptions causing losses of zinc production were frequent. Studies on leaching comprised the kinetics of ferrite leaching and jarosite precipitation, as well as the stability of jarosite in acidic plant solutions. A breakthrough came with the finding that jarosite could precipitate under conditions where ferrite would leach satisfactorily. Based on this discovery, a one-step process for the treatment of ferrite was developed. In the plant, the new process almost doubled the recovery of zinc from ferrite in the same equipment as the two-step jarosite process was operated in at that time. In a later expansion of the plant, investment savings were substantial compared to other technologies available. In the solution purification, the key finding was that Co, Ni, and Cu formed specific arsenides in the “hot arsenic zinc dust” step. This was utilized for the development of a three-step purification stage based on fluidized bed technology in all three steps, i.e. removal of Cu, Co and Cd. Both precipitation rates and selectivity increased, which strongly decreased the zinc powder consumption through a substantially suppressed hydrogen gas evolution. Better selectivity improved the value of the precipitates: cadmium, which caused environmental problems in the copper smelter, was reduced from 1-3% reported normally down to 0.05 %, and a cobalt cake with 15 % Co was easily produced in laboratory experiments in the cobalt removal. The zinc powder consumption in the plant for a solution containing Cu, Co, Ni and Cd (1000, 25, 30 and 350 mg/l, respectively), was around 1.8 g/l; i.e. only 1.4 times the stoichiometric demand – or, about 60% saving in powder consumption. Two processes for direct leaching of the concentrate under atmospheric conditions were developed, one of which was implemented in the Kokkola zinc plant. Compared to the existing pressure leach technology, savings were obtained mostly in investment. The scientific basis for the most important processes and process improvements is given in the doctoral thesis. This includes mathematical modeling and thermodynamic evaluation of experimental results and hypotheses developed. Five of the processes developed in this research and development program were implemented in the plant and are still operated. Even though these processes were developed with the focus on the plant in Kokkola, they can also be implemented at low cost in most of the zinc plants globally, and have thus a great significance in the development of the electrolytic zinc process in general.

Response of weed populations to tillage, reduced herbicide and fertilizer rates in wheat (Triticum aestivum) production

Field experiments were carried out in 1999 and 2000 to investigate the effects of conventional (CT) and no-tillage (NT) systems, interacting with three herbicide dose levels and three nitrogen (N) levels on weed growth and wheat production of two varieties. There was a higher grain yield for NT system compared with CT in one year. CT weed biomass was lower than from NT weed biomass, in both varieties. No differences on wheat biomass and grain yield were observed between full and reduced herbicide rates. N fertilizer increased wheat biomass and grain yield significantly. Only N medium level had an effect upon weed biomass with respect to non-fertilized plots, while the highest fertilization rate lowered weed biomass. Conventional tillage, reduced herbicide rates and nitrogen fertilization were effective ways of limiting weed production in wheat.

Rice seedling and plant development as affected by increasing rates of penoxsulam under controlled environments

Rice is a major staple in many countries. Weed control is one of the factors limiting higher rice yield. ALS (acetolactate synthase)-inhibiting herbicides are desirable weed control herbicides because of their high efficacy, low toxicity to mammalians, and low rates used. An important herbicide characteristic is high selectivity to the crop, since it facilitates fast crop establishment and greater crop advantage over the weeds. The objectives of this work were to study the effects of increasing rates of the ALS-inhibiting herbicide penoxsulam on seed integrity and germination, and seedling and plant development of rice cv. BRS Pelota under controlled laboratory and greenhouse conditions. The results showed that penoxsulam affected rice germination and seedling and plant growth at rates above 54 g a.i. ha-1, and that penoxsulam is safe for rice seedling development at the currently recommended rates.

Towards sustainable Iron- and steelmaking with economic optimization

The iron and steelmaking industry is among the major contributors to the anthropogenic emissions of carbon dioxide in the world. The rising levels of CO2 in the atmosphere and the global concern about the greenhouse effect and climate change have brought about considerable investigations on how to reduce the energy intensity and CO2 emissions of this industrial sector. In this thesis the problem is tackled by mathematical modeling and optimization using three different approaches. The possibility to use biomass in the integrated steel plant, particularly as an auxiliary reductant in the blast furnace, is investigated. By pre-processing the biomass its heating value and carbon content can be increased at the same time as the oxygen content is decreased. As the compression strength of the preprocessed biomass is lower than that of coke, it is not suitable for replacing a major part of the coke in the blast furnace burden. Therefore the biomass is assumed to be injected at the tuyere level of the blast furnace. Carbon capture and storage is, nowadays, mostly associated with power plants but it can also be used to reduce the CO2 emissions of an integrated steel plant. In the case of a blast furnace, the effect of CCS can be further increased by recycling the carbon dioxide stripped top gas back into the process. However, this affects the economy of the integrated steel plant, as the amount of top gases available, e.g., for power and heat production is decreased. High quality raw materials are a prerequisite for smooth blast furnace operation. High quality coal is especially needed to produce coke with sufficient properties to ensure proper gas permeability and smooth burden descent. Lower quality coals as well as natural gas, which some countries have in great volumes, can be utilized with various direct and smelting reduction processes. The DRI produced with a direct reduction process can be utilized as a feed material for blast furnace, basic oxygen furnace or electric arc furnace. The liquid hot metal from a smelting reduction process can in turn be used in basic oxygen furnace or electric arc furnace. The unit sizes and investment costs of an alternative ironmaking process are also lower than those of a blast furnace. In this study, the economy of an integrated steel plant is investigated by simulation and optimization. The studied system consists of linearly described unit processes from coke plant to steel making units, with a more detailed thermodynamical model of the blast furnace. The results from the blast furnace operation with biomass injection revealed the importance of proper pre-processing of the raw biomass as the composition of the biomass as well as the heating value and the yield are all affected by the pyrolysis temperature. As for recycling of CO2 stripped blast furnace top gas, substantial reductions in the emission rates are achieved if the stripped CO2 can be stored. However, the optimal recycling degree together with other operation conditions is heavily dependent on the cost structure of CO2 emissions and stripping/storage. The economical feasibility related to the use of DRI in the blast furnace depends on the price ratio between the DRI pellets and the BF pellets. The high amount of energy needed in the rotary hearth furnace to reduce the iron ore leads to increased CO2 emissions.

Novel technology for preparation of optically active chemicals

Asymmetric synthesis using modified heterogeneous catalysts has gained lots of interest in the production of optically pure chemicals, such as pharmaceuticals, nutraceuticals, fragrances and agrochemicals. Heterogeneous modified catalysts capable of inducing high enantioselectivities are preferred in industrial scale due to their superior separation and handling properties. The topic has been intensively investigated both in industry and academia. The enantioselective hydrogenation of ethyl benzoylformate (EBF) to (R)-ethyl mandelate over (-)-cinchonidine (CD)-modified Pt/Al2O3 catalyst in a laboratory-scale semi-batch reactor was studied as a function of modifier concentration, reaction temperature, stirring rate and catalyst particle size. The main product was always (R)-ethyl mandelate while small amounts of (S)-ethyl mandelate were obtained as by product. The kinetic results showed higher enantioselectivity and lower initial rates approaching asymptotically to a constant value as the amount of modifier was increased. Additionally, catalyst deactivation due to presence of impurities in the feed was prominent in some cases; therefore activated carbon was used as a cleaning agent of the raw material to remove impurities prior to catalyst addition. Detailed characterizations methods (SEM, EDX, TPR, BET, chemisorption, particle size distribution) of the catalysts were carried out. Solvent effects were also studied in the semi-batch reactor. Solvents with dielectric constant (e) between 2 and 25 were applied. The enantiomeric excess (ee) increased with an increase of the dielectric coefficient up to a maximum followed by a nonlinear decrease. A kinetic model was proposed for the enantioselectivity dependence on the dielectric constant based on the Kirkwood treatment. The non-linear dependence of ee on (e) successfully described the variation of ee in different solvents. Systematic kinetic experiments were carried out in the semi-batch reactor. Toluene was used as a solvent. Based on these results, a kinetic model based on the assumption of different number of sites was developed. Density functional theory calculations were applied to study the energetics of the EBF adsorption on pure Pt(1 1 1). The hydrogenation rate constants were determined along with the adsorption parameters by non-linear regression analysis. A comparison between the model and the experimental data revealed a very good correspondence. Transient experiments in a fixed-bed reactor were also carried out in this work. The results demonstrated that continuous enantioselective hydrogenation of EBF in hexane/2-propanol 90/10 (v/v) is possible and that continuous feeding of (-)-cinchonidine is needed to maintain a high steady-state enantioselectivity. The catalyst showed a good stability and high enantioselectivity was achieved in the fixed-bed reactor. Chromatographic separation of (R)- and (S)-ethyl mandelate originating from the continuous reactor was investigated. A commercial column filled with a chiral resin was chosen as a perspective preparative-scale adsorbent. Since the adsorption equilibrium isotherms were linear within the entire investigated range of concentrations, they were determined by pulse experiments for the isomers present in a post-reaction mixture. Breakthrough curves were measured and described successfully by the dispersive plug flow model with a linear driving force approximation. The focus of this research project was the development of a new integrated production concept of optically active chemicals by combining heterogeneous catalysis and chromatographic separation technology. The proposed work is fundamental research in advanced process technology aiming to improve efficiency and enable clean and environmentally benign production of enantiomeric pure chemicals.

Behavior of RR soybeans subjected to different formulations and rates of glyphosate in the reproductive period

Recent studies indicate that glyphosate applied in post-emergence in RR soybean can eventually cause phytotoxic effects. However, there are many questions that need to be clarified in the scientific and technical contexts, involving the issue of RR soybeans regarding the use of glyphosate. This study has assessed the impact of the application of different doses and formulations of glyphosate in the reproductive period of RR soybean (R1 stage). For that purpose, an experiment in the field was conducted in two harvests (2011/12 and 2012/13), in which a 2 x 5 factorial design was used (formulations versus doses) totaling 10 treatments. In these two experiments the variables related to agronomic performance were: phytotoxicity (7, 14, 21 and 28 days after application), plant height, number of pods per plant, yield and weight of 100 grains (end of soy cycle). The results obtained allowed characterizing phytotoxicity and damages to the height and yield in RR soybean, with increasing rates of glyphosate applied in the reproductive period.

MANAGEMENT OF MAIZE STOVER WITH UNDERDOSES RATES OF GLYPHOSATE APPLICATIONS IN NO-TILLAGE

ABSTRACTGlyphosate has significant effects on the growth and development of plants when in underdoses. This work was developed to verify the effect of the application of glyphosate in underdoses in lignin synthesis and consequently decomposition of maize stover. Two experiments were conducted; the first one in a greenhouse for underdoses adjustments and the second one in the production area. The experimental design of the first trial was completely randomized with four replications. The treatments consisted in the application of the underdoses: 0, 25, 50 and 100 g ha-1 of glyphosate. In the production area, the experimental design was a randomized block with four replications, in underdoses: 0, 12.5, 25 and 50 g ha-1. The results were submitted to analysis of variance and regression. The underdoses of 25 g a.e. ha-1in a greenhouse promoted 36% increase in productivity of stover, in addition to increasing the lignin content in 16%, with no change in the unwanted growth of maize plants. In the production area, the concentration of 12.5 g a.e. ha-1 of glyphosate reduced the lignin content and the other underdoses have not changed this feature in maize plants. None of the underdoses affected the height and biomass produced by the maize plants. The highest underdose tested promoted acceleration in the decomposition of maize stover.

“Between publication culture and funder mandates - What is the future for disciplinary repositories?”

Workshop at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

The Purdue University Research Repository (PURR): An institutional data management service with a virtual research environment, data publication, and archiving

Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

A Model for Integrating the Publication and Preservation of Journal Articles

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Influence of body mass and environmental oxygen tension on the oxygen consumption rates of an enteropneust, Glossobalanus crozieri

The present study deals with a species of enteropneust, Glossobalanus crozieri, focusing on two aspects of its respiration: a) oxygen consumption and body mass, and b) the influence of environmental oxygen tension on the respiratory rate. Preliminarily, the body water content was shown to be 85% of the whole body weight. The regression coefficient of the oxygen consumption on the wet body mass (0.578) seems to agree with the view that in enteropneusts respiration is mainly cutaneous. The respiratory rate was significantly reduced at O2 tensions from 76 mmHg downwards, suggesting conformity rather than regulation

Comparing adult-youth and adult-adult online sexual solicitation: Manipulative behaviors, situational factors, and outcomes

Online sexual solicitation (solicitation) of youth has received widespread media and research attention during the last decade. The prevalence rates of youth who have experienced solicitation or solicitation attempts vary between studies depending on the methodology used (e.g., whether youth or adults are the target study group). In studies focusing on youth victims, the prevalence of solicitation attempts made by adults during the past year is typically reported to be between 5 and 9%. Adults who solicit youth online have been found to use deception and other manipulative behaviors to gain access to sexual activities with youth. However, previous studies have lacked a control group of adults who solicit other adults online. Without this comparison, one could argue that deceiving others online about one’s identity, and engaging in manipulative behaviors, is an inherent part of most online sexual interactions with strangers. Additionally, little is known about the associations between manipulative behaviors and the solicitation outcomes. In research concerning offline sexual behaviors, it has been noted that situational factors, such as sexual arousal, may alter both sexual interest and behavior. The effects of situational factors on online sexual behaviors have been less extensively studied (especially so with a quantitative approach); no studies have to date focused on adults’ solicitation of youth. Investigating the role of a lowered sexual age preference and the role of situational factors in the soliciting adults could be an important step in order to receive deeper knowledge of the role of traits and states in the context of solicitation. Additionally, there is a lack of knowledge of the effect of the age of the youth. Although previous studies on solicitation has found that older youth, compared with younger youth and children, are more often solicited, the possible reasons for this have not been investigated. Are adults who solicit youth affected by legal deterrence (through the legal age of consent), is it because older youth are more available online, or are the adults’ age preferences merely a product of a normally distributed age preference in the population? The purpose of the present thesis was fivefold: 1) to obtain an estimate of the frequency of adults’ solicitation of youth as self-reported and observed in actual behavior; 2) to explore whether the legal age of consent (LAC) affects solicitation frequency, or whether a normally distributed sexual age preference more accurately describe the proportion of solicited youth of different ages; 3) to investigate the associations of both traits (e.g., lower sexual age preference) and states (immediate situational factors, such as alcohol intoxication), and the solicitation target; 4) to explore whether adults who solicit youth and adults who solicit adults are equally deceitful and manipulative online, and whether the different solicitation outcomes are as common in both groups; and 5) to investigate whether the deceitful and manipulative behaviors engaged in had different associations with the solicitation outcomes depending on the age of the solicited. In the survey study, a convenience sample of 1393 adult participants (aged 18 years or older) self-reported any online communication with strangers during the past year. Of these, 56% (776 respondents) reported that they had solicited or attempted to solicit at least one stranger. Of the respondents, 453 (58.4%) were men, and 323 (41.6%) were women. Participants with only adult contacts (18 years or older) constituted the majority (640 respondents). In contrast, 136 individuals reported a youth contact (a 13 year old or younger, or a 14 to 17-year old). Approximately half of the participants were men in the adult contact group, while 75% of the participants were men in the youth contact group. Approximately 60% of the participants with youth contacts were recruited from two websites associated with a pedophilic sexual interest. In an online quasi-experimental study, with researchers impersonating youth of different ages (10–18 year olds) in chat rooms, 251 online conversations with chat room visitors made up the entire sample. All chat room visitors alleged to be men. The self-reported frequency of having solicited youth (0–17-year olds) during the past year was approximately 10% in our sample of adults who reported communicating with any strangers online. When we observed this behavior in chat rooms, we found that approximately 30% of the chat room visitors who believed they interacted with a 10 to 14 year old attempted to solicit the youth. We found that solicitation attempts increased equally much when increasing the age of the impersonated youth from 14 to 16, as from 16 to 18. Thus, we concluded that a normally distributed age preference in the population was a more plausible explanation to the effect of the age of the solicited, rather than the LAC (here; 15 and 16). If the chat room visitors would have been deterred only by the LAC, we would have expected that the change in amount of solicitation attempts from an illegal age group to a legal age group would have been significantly stronger than changes between age groups within illegal-illegal and legal-legal groups. Our subsample of survey participants from the pedophilia-related websites expectedly reported that they had solicited youth more often in comparison to the sample gathered through general (i.e., not associated with any particular sexual preference) websites. We also found that participants with a youth contact reported higher levels of sexual arousal and shame before the sexual interaction with their online contact, compared with participants with an adult contact. Additionally, the participants with youth contacts who reported consumption of child- and adolescent pornography also reported being more sexually aroused before the interaction, compared to the participants with youth contacts who did not report consumption of these kinds of pornography. We also found clear indications that the online sexual interaction had an alleviatory effect on reported levels of sadness, boredom and stress, independent of the age of the contact. Generally, the participants with youth and adult contacts reported deceiving their contacts as often and suggesting keeping the communication a secret from someone as often. Participants with a youth contact, however, reported using more persuasion techniques for online sexual purposes or for the purpose of an offline meeting, compared to those with an adult contact. In the chat rooms, we found that more indirect ways of future sexual communication (e.g., continuing chatting) was suggested by the chat room visitors that were under the assumption of interacting with youth aged 10 to 14, compared with more direct means (e.g., meeting offline). Survey participants with youth contacts who had used deception, suggested keeping the interactions a secret, and/or persuaded their contact by appealing to the contacts feelings of love and attachment for the participant had also more often engaged in cybersex with the contact. No other manipulative behaviors were associated with the other investigated solicitation outcomes (receiving a sexual picture, meeting offline, and engaging in sexual contact offline) within this group of participants. However, using deception, suggesting secrecy and using persuasion was also positively associated with certain solicitation outcomes within participants with an adult contact. In summary, adults’ solicitation of youth is much more frequent when observed in chat rooms than self-reported. Additionally, an underlying lowered sexual age preference seems to be a motivating factor on a group level in adults who solicit youth. We concluded that directed prevention efforts should be made on pedophiliarelated websites. Additionally, the role of situational factors, especially sexual arousal in persons with a pedo- or hebephilic sexual interest should be investigated further in the context of online sexual solicitation.

Eradication of Helicobacter pylori infection in patients with duodenal ulcer and non-ulcer dyspepsia and analysis of one-year reinfection rates

Helicobacter pylori (HP) infection is endemic worldwide. The proposed treatment is expensive and there are few reports regarding reinfection rates in Brazil. The aim of this study was to compare the eradication rates obtained with two therapeutic options and to evaluate reinfection one year after treatment. This was a prospective randomized trial with 55 patients. Thirty-nine patients had active duodenal ulcer (DU) and 16 non-ulcer dyspepsia (NUD), and all tested positive for HP. Diagnosis was based on at least two positive tests: ultrarapid urease test, histology and/or culture. Patients were randomized to two groups: group OMC treated with 40 mg omeprazole (once a day), 500 mg metronidazole and 250 mg clarithromycin (twice daily) for 7 days, or group NA treated with 300 mg nizatidine (once a day) and 1000 mg amoxicillin (twice daily) for 14 days. Those patients in whom HP was eradicated were followed up for one year to evaluate reinfection. Twenty-five patients were randomized for OMC and 30 for NA. HP eradication occurred in 20/25 patients (80%) treated with OMC and 13/30 (43%) treated with NA (P = 0.01). After reallocation because of initial treatment failure, the overall eradication rate was 44/51 patients (86%). After an average follow-up of one year, we evaluated 34 patients (23 with DU and 11 with NUD). Reinfection occurred in 3/34 patients (7.6%). We conclude that OMC is effective for HP eradication, and that NA should not be used. Reinfection occurs in 7.6% of the patients in the first year after eradication.