This work deals kinetics of grinding Portland cement clinker which is influenced by addition of grinding inlays surfactants. In an experiment, attritor-type stirred mill was used and surface active grinding additives such as polyethylenglykol (PEG), triethylamin (TEA) and acetate of ammonium were utilized. Granulometric distribution graph obtained from laser diffraction analysis provides data for plotting development diagrams for milling process.

This work deals with the study of limestone and corundum dry milling using attritor-type stirred mill in a batch mode. There were stearin and polyethylene glycol used as surfactants and spherical shaped steel grinding elements used for the experimental part of the work. The main idea was to examine behavior of the selected grinding stock type within a long-term grinding forces exposure in selected conditions of ultrafine dry milling leading up to the submicron area. Characterization of samples was performed by laser granulometry, X-ray powder diffraction analysis, flame atomic absorption spectroscopy, objective color determination and electrokinetic potential measurement. Experimetaly measured data implies that in all cases there was a re-agglomeration of the grinding stock particles occurring, although in different stages of the disintegration process and in mutually various degree. The analysis results denote that a larger erosion of the crystal structures with the associated increase of the amorphous phase in the submicron particle size took place in the grinding stock.

Pollutant control and efficiency improvement propel the need for clean combustion research on internal combustion engines. To design cleaner fuels for advanced combustion engines, gasoline combustion chemistry must be both understood and developed. A comprehensive examination of gasoline combustion chemistry in a jet stirred reactor is introduced in this dissertation. Real gasoline fuels have thousands of hydrocarbon components, which complicate numerical simulation. To mimic the behavior of real gasoline fuels, surrogates, composed of a few hydrocarbon components, are offered as a viable approach. In this dissertation, combustion chemistry of n-heptane, a key surrogate component, is investigated first, followed by an evaluation of a surrogate kinetic model. Finally, real gasoline fuels are assessed with the surrogate kinetic model. Mass spectrometry was employed to measure intermediates in n-heptane low temperature chemistry. Reaction pathways of the observed intermediates were proposed and clarified. n-Heptane low temperature oxidation reaction scheme was expanded by the proposed reactions. After surrogate proposal and formation, a surrogate kinetic model was examined. Low temperature and high temperature chemistry were observed and predicted. The octane number and composition effect on low temperature oxidation reactivity were revealed. High temperature combustion chemistry was found to be similar among the different surrogates, and the surrogate kinetic model reproduced surrogate behavior well in both low and high temperatures. Finally, the proposed surrogate model was examined using real gasoline fuels. Five real FACE (fuel for advanced combustion engines) gasolines were selected as target fuels to cover a wide range of octane number, sensitivity and hydrocarbon compositions. Low temperature oxidation chemistry was investigated for two intermediate octane number gasolines, FACE A and C. For a high octane number gasoline, FACE F, key pollutant production pathways were the focus of high temperature combustion chemistry. Two low octane number gasolines, FACE I and J, were compared with three other FACE gasolines to clarify gasoline combustion chemistry over a wide range. The gasoline surrogate chemical kinetic model proved to be a comprehensive, viable, accurate and powerful approach for numerical simulations. The proposed gasoline surrogate chemical kinetic model can aid in the numerical design of advanced combustion engines.

Particle breakage can be significant in stirred vessels such as crystallizers. During crystallization, particle breakage can occur due to particle contact with other particles, the impeller, the suspension fluid, and/or the vessel. Such breakage produces fines and can cause filter plugging downstream. Although research has been conducted with respect to particle breakage, a comprehensive study is still needed to quantify the breakage occurring in stirred vessels. The overall goal of this research is to model the particle breakage occurring in a stirred vessel by analyzing the particle size and shape distributions that result from breakage. Breakage experiments are based on collision influences that affect the two dominant collisions types, crystal-to-crystal and crystal-to-impeller collisions. Results showed that the quantity of fines produced are affected by the solids concentration or magma density and suspension fluid utilized. Additionally, aqueous saturated solutions produced particle size distributions that differ from those obtained using a nonsolvent. Similar particle size distributions for two different materials (NaCl and KCl) are achieved in the same nonsolvent (acetonitrile) by adjusting the agitation rate using the Zwietering correlation to account for property differences; moreover, the same agitation rate adjustment produced similar distributions for KCl in acetone and acetonitrile which were both nonsolvents. However, modifications to the Zwietering correlation, such as changing the significance of the initial particle size, are proposed before this method of adjustment is deemed accurate. Number-based population modeling of particle breakage is achieved within 1-5% error for NaCl at each agitation rate investigated. Breakage modeling using a discretized population balance equation with Austin's equation for attrition and the power law form of the product function for fragmentation is a viable approach; however, more work is needed to increase the accuracy of this model.

The global demand for food is increasing. Different nutrients are used to increase growth in agriculture and are thus essential for the world ́s food supply. An important and common nutrient is phosphorus. It can be mined, in the form of phosphate, from phosphate rock. The problem is that mining causes environmental problems and phosphate rock is a non-renewable resource. A risk is that phosphorus will become a scarce commodity in about 100 years.  Sewage sludge from wastewater treatment plants (WWTP) is rich in phosphorus. In Sweden and other European countries, a stricter legislation is expected with consideration of an increased recovery of phosphorus from sewage sludge. A ban on the spread of hazardous substances like drug residues and heavy metals from the sludge is also expected. Incineration of the sludge can be done to eliminate hazardous substances and at the same time recover phosphorus and metals. Development of technologies to recover phosphorus from incinerated sewage sludge is therefore topical.  EasyMining is a company that invents new technologies to close nutrient cycles. One of their present projects is about recycling phosphorus, iron, and aluminium from incinerated sewage sludge. Hydrochloric acid (HCl) is used to leach the ash and in the following steps metals and phosphorus are recovered, and heavy metals are removed. Batch experiments have been performed and EasyMining examines the process in a continuous stirred tank reactor (CSTR).  The aim with this project is to compare the batch and continuous process for the ash leaching step. The study was limited to investigate different residence times and liquid to solid ratios (L/S ratios) for the ash leaching step in the CSTR. To accomplish the aim, mainly experimental studies have been performed. A total of 14 runs have been conducted to investigate the continuous process. The residence times 10, 30 and 60 min and the L/S ratios 2.5, 3 and 3.5 ml/g were evaluated. The lab-set up consisted of a peristaltic pump to pump diluted HCl solution, a conveyor belt to dose the ash and a CSTR. The filtrate was analysed for phosphorus, iron, and aluminium with a spectrophotometer. Interpretation of the result was conducted after each run and the data was then compared to previous batch data from within the company. A paired t-test was used to evaluate if there was a significant difference in the mean values between different residence times and L/S ratios.  The result shows that the leching is very fast and longer residence times or higher L/S ratios do not result in higher yields for phosphorus, iron, or aluminium. There is no significant difference between the examined residence times or L/S ratios in the paired t-test. Data from the batch process shows that the investigated residence times and L/S ratios do not affect the yield. A more even distribution of the yields is obtained in the batch process compared to the continuous process. The less even distribution in the continuous process, probably depends on errors in the method and the equipment used in the process. For example, there were some problems with the ash dosing, which led to an inconstant L/S ratio in the runs. This affected the calculated yields significantly. Overall, the batch process results in slightly higher yields. This is especially the case when excluding high calculated yields in the continuous process, probably obtained because of an overdosing of the ash. / Den globala efterfrågan på mat ökar. Olika näringsämnen används för att få en högre tillväxt i jordbruket och dessa är essentiella för världens livsmedelsproduktion. Ett viktigt och vanligt näringsämne är fosfor och det bryts i form av fosfat från fosfatmineral. Problemet är att brytningen förorenar miljön och dessutom är fosfat-sten en icke förnyelsebar resurs. Det finns en risk att fosfor blir en bristvara om cirka 100 år.  Avloppsslam från vattenreningsverk innehåller höga fosfatkoncentrationer. I Sverige samt i andra europeiska länder förväntas en striktare lagstiftning, som kräver en ökad återvinningsgrad av fosfor från avloppsslam. Även ett förbud mot spridningen av giftiga substanser som läkemedelsrester och tungmetaller förväntas införas. Slammet kan förbrännas för att eliminera farliga substanser samtidigt som fosfor och olika metaller kan återvinnas. Utvecklingen av nya tekniker för återvinning av fosfor från bränt avloppsslam är därför väldigt aktuell.  EasyMining är ett innovationsföretag som utvecklar nya tekniker för att erhålla slutna näringskretslopp. Ett av deras pågående projekt handlar om att återvinna fosfor, aluminium och järn från förbränt avloppsslam. Saltsyra används för att laka askan och i nästkommande steg återvinns fosfor och metaller, samtidigt som tungmetaller separeras. Satsvisa försök har genomförts och EasyMining vill nu undersöka processen i en tankreaktor.  Syftet med projektet är att jämföra resultat från den satsvisa driften med resultat från en kontinuerlig process för ask-lakningssteget. Studien begränsades till att endast undersöka olika uppehållstider och förhållandet mellan vätskan och askan (L/S-förhållande) i lakningssteget. För att uppnå syftet genomfördes huvudsakligen experimentella studier. 14 körningar genomfördes totalt för undersökning av den kontinuerliga processen. Undersökta uppehållstider var 10, 30 och 60 min och undersökta L/S-förhållandena var 2,5, 3 och 3,5 ml/g. Laborationsuppställningen bestod av en peristaltisk pump för tillförsel av utspädd saltsyralösning, ett rullband för dosering av askan samt en tankreaktor. Filtratet analyserades för fosfor, järn och aluminium i en spektrofotometer. Efter varje körning tolkades resultatet och jämfördes därefter med data från de av företaget tidigare utförda satsvisa försöken. Ett parat t-test användes för att utvärdera om det fanns någon signifikant skillnad i medelvärden mellan olika uppehållstider och L/S-förhållanden.  Resultatet visar att lakningen är väldigt snabb och längre uppehållstider eller högre L/S-förhållanden ger inte högre utbyten för fosfor, järn eller aluminium. Ingen signifikant skillnad erhålls mellan undersökta uppehållstider eller L/S-förhållanden i de parade t-testen. Data från de satsvisa försöken visar att de undersökta uppehållstiderna och L/S-förhållandena inte påverkar utbytet. En mindre spridning av utbyten erhålls i den satsvisa driften jämfört med den kontinuerliga. Den större spridningen i den kontinuerliga processen beror förmodligen på felkällor i processens metod/utrustning. Exempelvis var det en del problem med askdoseringen, vilket medförde icke konstanta L/S-förhållanden. Detta påverkade det beräknade utbytet signifikant. Generellt erhålls något högre utbyten i den satsvisa processen. Framförallt då höga beräknade utbyten exkluderas i den kontinuerliga processen på grund av en överdosering av askan.

This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).

An introduction is given to the background theory and scientific literature of the major subject areas of interest in this thesis, namely the chemistry of free radical and anionic polymerisation, molecular weight control in each type of polymerisation, polymerisation reactors, computer simulation of polymerisation processes and polymer characterisation by gel permeation chromatography. A novel computer model has been devised, based on the analysis of the polymerisation process in terms of the reaction extent of each reactant and the use of generation functions to describe the concentration of living and dead polymeric species, for the free radical, solution polymerisation of methylmethacrylate in a CSTR. Both heat and mass balance expressions have been described. Conversion, Mn and Mw were monitored. To test the model a reactor was designed and constructed. A detailed description of the reactor and the experimental conditions used for the validation of the model are given. The results of these studies are presented and excellent agreement is shown between model predictions and experiments up to 30% conversion for Mn w and % conversion. A similar study is described for the anionic polymerisation of styrene in tetrahydrofuran as solvent, in a CSTR. In this work the computer model becomes 'stiff' when realistic rate constants are introduced in the kinetic expressions. Experimental difficulties were encountered in obtaining reproducible results in the anionic work. A new approach of using 'scavengers' as protecting agents for the living chains is described. A scavenger was successfully employed in the preparation of block copolymers using a tubular reactor. Block copolymerisation, in addition to providing a means of checking the number of the 'living' chains inside the reactor, is of interest in its own right. All the experimental findings are discussed in relation to the currently accepted views found in the scientific literature.

An optimal stochastic feedforward-feedback control scheme is implemented on a heat exchanger-stirred tank system using an on-line minicomputer. Because variations in the measured disturbance variable have an effect on the output controlled variable before compensating action can become effective, the feedforward action must be predictive in nature. Statistical time series models are used to model both the measured disturbance and the unobserved disturbances in the system. These stochastic disturbance models and the transfer function models for the process are identified, fitted and checked using statistical model building procedures on a set of data collected on-line using the minicomputer. The predictive feedforward-feedback controller is derived from these models. The performance of the control scheme is compared with that of a pure feedback control scheme and the actual performances are shown to conform well to the theory. / Thesis / Master of Engineering (ME)

No description available.

No description available.