Shrinking core models applied to the sodium silicate production process

The sodium silicate production process, with the molar ratio SiO2/Na2O = 2, for detergent zeolite 4A production, is based on quartz sand dissolving in NaOH aqueous solution, with a specific molality. It is a complex process performed at high temperature and pressure. It is of vital importance to develop adequate mathematical models, which are able to predict the dynamical response of the process parameters. A few kinetic models were developed within this study, which were adjusted and later compared to experimental results. It was assumed that SiO2 particles are smooth spheres, with uniform diameter. This diameter decreases during dissolving. The influence of particle diameter, working temperature and hydroxide ion molality on the dissolution kinetics was investigated. It was concluded that the developed models are sufficiently correct, in the engineering sense, and can be used for the dynamical prediction of process parameters. Proces dobijanja natrijum silikata, molamog odnosa SiO2/Na2O) = 2 za potrebe proizvodnje deterdzentskog zeolita 4A se bazira na rastvaranju cestica kvarcnog peska u vodenom rastvoru NaOH odredjenog molaliteta. To je slozen proces pri povisenim temperaturama i pritiscima. Za ovakav proces je veoma bitno postaviti odgovarajuci model pomocu koga bi se moglo predvidjen dinamicko ponasanje parametara procesa. U ovom radu razvijeno je nekoliko kinetickih modela, koji su poredjeni sa eksperimentalnim rezultatima, pri cemu je usvojeno da su cestice Si02 glatke sfere, uniformnog precnika. Precnik tih cestica se smanjuje tokom procesa rastvaranju. Ispitivani su uticaji velicine cestice, radne temperature i molaliteta hidroksidnog jona na kinetiku rastvaranju. Zakljuceno je da su razvijeni modeli dovoljno tacni, u inzenjerskom smislu i da se kao takvi mogu koristiti za kvalitetno predvidjanje dinamickog ponasanja parametara procesa.