This study was carried out with Beypazari trona ore having a grade about 85 % trona (Na2CO3.NaHCO3.2H2O). The main target of the study is the determination of calcinations and leaching parameters, which are the two main unit operations in the production of soda ash (Na2CO3) from trona ore. Calcination parameters / calcination duration, calcination temperature and particle size were determined by using three different heat treatment systems, namely laboratory type muffle furnace, up draught furnace and microwave oven. As an alternative, wet type microwave-induced calcination which completes the decomposition of trona in solution was also investigated. Thirty minutes of calcination time was sufficient for complete calcination of &amp / #8211 / 6.35 mm trona sample at 175 &deg / C with the muffle furnace. Calcination of trona with microwave treatment was completed in a shorter time. The nature of thermal reactions and structural changes of trona during calcination were elucidated by TG (Thermogravimetry), DTG (Derivative Thermogravimetry), SEM (Scanning Electron Microscope) and XRD (X-ray diffraction) analysis. The effect of heat treatment on grindability, specific surface area and decrepitation of trona were also investigated. In the last stage of the study, leaching parameters / leaching time, leaching temperature and pulp density were determined for both uncalcined and calcined samples. 80 % leach recovery was obtained in 4 minutes for &amp / #8211 / 6.35 mm particle size of uncalcined sample in 25 % pulp density while 100 % leach recovery was reached for the calcined samples under the same conditions.

Solar evaporite systems are man-managed ecosystems which are highly vulnerable to biological,physical and chemical disturbances. The problems encountered in such systems are in many cases found to be associated with the microbial ecology and the design of the system. This project focussed on investigating the nature of organic compounds contaminating soda ash produced at a solar evaporite production system located at Sua Pan in Botswana. Several years after the plant was commissioned, problems, including accumulation of total organic carbon (TOC) and discolouration of the soda ash product were encountered. The salt produced also retained high moisture content and was coloured pink. These phenomena impacted severely on the economic performance of the enterprise. This study was aimed at determining the origin and fate of these organic compounds within the system in order to elucidate the nature of the problem and also to conceptualise a remediation strategy suitable to reducing its impact. This was achieved by analysis of both dialysed and solvent extracts of the influent brine (well-brine), brine in the ponds (T-brine) and the bicarbonate filter cake. Although complete identification of the organic compounds isolated was not undertaken in this study, spectroscopic analysis of compounds isolated, by UV, IR, NMR and MS, strongly indicated that fulvic acids, a component of the influent well-brine organics, contribute to the organic contamination of the final product. Part of this component, however, is degraded during the ponding process. It was shown that an extracellular polysaccharide (EPS) produced by Dunaliella. spp., which proliferates in the evaporation ponds, contributes in a major way to the accumulation of TOC in the system. This was demonstrated by relating the sugar profile of carbohydrates isolated from the pond brine and final product, being arabinose, xylose, 2-o-methyl hexose, mannose, glucose and galactose. Studies reported show that EPS production was enhanced when algal cultures were exposed to stress conditions of high illumination, increasing salinity and temperature, and nitrogen limitation. Studies undertaken for the development of a remediation process for this system have shown that nutrient stripping and bacterial systems could be applied to deal with the dissolved TOC fraction, whereas adsorption systems could deal with the particulate fractions. Algal systems showed most potential for the removal of nutrients in the influent well-brine compared to chemical processes.Complete removal of ammonium and phosphorus removal efficiencies of pproximately 50% were achieved in an unoptimised pilot-scale Dunaliella-based HRAP. While similar effects were demonstrated for chemical processes, some economic constraints were noted. The potential of halophilic bacterial systems for the degradation of organic compounds in brine was also demonstrated. The limitations on the performance of such systems, associated with the low metabolic diversity, and poor immobilisation of physico-chemical processes were found to have a very low impact on the dissolved TOC fraction of the brine, the removal of the particulate material was found to result in a 35% TOC reduction in the final soda ash product and the production of a white final product.halobacteria, however, were noted. Although physico-chemical processes were found to have a very low impact on the dissolved TOC fraction of the brine, the removal of the particulate material was found to result in a 35% TOC reduction in the final soda ash product and the production of a white final product. Apart from a description of the microbial ecology of the ponds and the identification of major contributions to the TOC of the final product, a number of remediation strategies were evaluated and are described. These include chemical and biological stripping of nutrients sustaining microbial TOC production in the ponds, and also biological and physico-chemical processes for their removal once formed. Future studies to undertake the further development of these proposals has been described

<p>The aim of the project was to study the manufacturing of synthetic soda ash (sodium carbonate, Na2CO3) on an industrial scale. Currently all Soda ash that is used in South Africa for manufacturing glass is imported at a high cost, and the company Nampak Wiegand Glass (South Africa) is investigating the possibility to locally manufacture synthetic soda ash. About 75% of soda ash is synthetically produced from either the Leblanc process, Solvay process, Modified Solvay (Dual) process or dry lime process. This study concentrated on the Solvay process on a laboratory scale for eventual input into a larger pilot plant. The produced material was analyzed using analytical techniques such as FTIR (Fourier Transform Infrared spectroscopy), Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Atomic Emission spectroscopy (ICP-AES). There are certain standard requirements for impurities in the soda ash, and this needed to be measured and determined what changes to the process will bring the impurities to the required minimum standard. Environmental issues around the manufacturing process were also studied. After completing of the laboratory experiments and the extraction of required data from the results, Nampak will use the information to decide on a followup to the building of a small pilot plant to further test and develop the engineering and economical aspects of a full plant. If successful a full scale manufacturing plant can be developed in South Africa for producing soda ash.&nbsp / This study thus will not only help Nampak Wiegand Glass in finalizing the decision to go ahead, but its result will also benefit other companies that use the soda ash in oil refining, water treatment, pulp and paper, chemical industry etc. Some parts of the work done will be proprietary to Nampak and subject to confidentiality agreement.</p>

<p>The aim of the project was to study the manufacturing of synthetic soda ash (sodium carbonate, Na2CO3) on an industrial scale. Currently all Soda ash that is used in South Africa for manufacturing glass is imported at a high cost, and the company Nampak Wiegand Glass (South Africa) is investigating the possibility to locally manufacture synthetic soda ash. About 75% of soda ash is synthetically produced from either the Leblanc process, Solvay process, Modified Solvay (Dual) process or dry lime process. This study concentrated on the Solvay process on a laboratory scale for eventual input into a larger pilot plant. The produced material was analyzed using analytical techniques such as FTIR (Fourier Transform Infrared spectroscopy), Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Atomic Emission spectroscopy (ICP-AES). There are certain standard requirements for impurities in the soda ash, and this needed to be measured and determined what changes to the process will bring the impurities to the required minimum standard. Environmental issues around the manufacturing process were also studied. After completing of the laboratory experiments and the extraction of required data from the results, Nampak will use the information to decide on a followup to the building of a small pilot plant to further test and develop the engineering and economical aspects of a full plant. If successful a full scale manufacturing plant can be developed in South Africa for producing soda ash.&nbsp / This study thus will not only help Nampak Wiegand Glass in finalizing the decision to go ahead, but its result will also benefit other companies that use the soda ash in oil refining, water treatment, pulp and paper, chemical industry etc. Some parts of the work done will be proprietary to Nampak and subject to confidentiality agreement.</p>

Abstract available in PDF copy. / Thesis (M.Sc.-Chemical Engineering)-University of Natal, 1988.

Magister Scientiae - MSc / The aim of the project was to study the manufacturing of synthetic soda ash (sodium carbonate, Na2CO3) on an industrial scale. Currently all Soda ash that is used in South Africa for manufacturing glass is imported at a high cost, and the company Nampak Wiegand Glass (South Africa) is investigating the possibility to locally manufacture synthetic soda ash. About 75% of soda ash is synthetically produced from either the Leblanc process, Solvay process, Modified Solvay (Dual) process or dry lime process. This study concentrated on the Solvay process on a laboratory scale for eventual input into a larger pilot plant. The produced material was analyzed using analytical techniques such as FTIR (Fourier Transform Infrared spectroscopy), Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Atomic Emission spectroscopy (ICP-AES). There are certain standard requirements for impurities in the soda ash, and this needed to be measured and determined what changes to the process will bring the impurities to the required minimum standard. Environmental issues around the manufacturing process were also studied. After completing of the laboratory experiments and the extraction of required data from the results, Nampak will use the information to decide on a followup to the building of a small pilot plant to further test and develop the engineering and economical aspects of a full plant. If successful a full scale manufacturing plant can be developed in South Africa for producing soda ash. This study thus will not only help Nampak Wiegand Glass in finalizing the decision to go ahead, but its result will also benefit other companies that use the soda ash in oil refining, water treatment, pulp and paper, chemical industry etc. Some parts of the work done will be proprietary to Nampak and subject to confidentiality agreement. / South Africa

Botswana Ash (Pty) Ltd which is situated in Sua Pan, north east Bostwana, is one of Africa's largest suppliers of salt and soda ash. For a number of years, the company has been experiencing problems which have resulted in the final soda ash product being contaminated and discoloured. The problems experienced at Sua Pan have been reported also to occur in other salt works all over the world. It has been suggested that contamination in many salt works could be possibly be due to the microbial activity by halophilic algae and bacteria that grow in the solar ponds. This study was undertaken to investigate the nature of the contaminating organic compounds present in the brine, to identify the compounds, and to establish how these components vary during the various stages of the soda ash processing. For this study, two sets of brine samples were used; the first set was collected before the summer rains and the second set was collected after the summer rains. Solid bicarbonate and soda ash samples were also used. Extractions, desalting, UV and HPLC analysis and oxidative biotransformations using four enzymes, were used for developing profiles and characterizing the brine components. From these studies, we were able to confirm that the components of the brine are organic in nature. A thorough study of one of the compounds isolated,from solid bicarbonate and soda ash was conducted using UV, HPLC, IR, NMR, HPLC-MS, GC-MS and TLC. The results of these analyses, show that the. isolated compound was benzyl butyl phthalate which is generally regarded to be humic in nature. This compound was found to be present in all the brine samples collected after the summer rains including the well brine, suggesting this compound occurs naturally and is not formed during the processing.