Priprava belega pigmenta iz hidratiziranega titanovega oksida

Okorn, Miha (author), Marinšek, Marjan (mentor)

V diplomski nalogi so predstavljeni procesi, ki potekajo v kalcinatorju oz. rotacijski peči med kalcinacijo na industrijskih vzorcih hidratiziranega titanovega dioksida. Vzorci so bili narejeni po sulfatnem postopku in za termično analizo odvzeti iz podjetja Cinkarna Celje, d. d. Kalcinacija se deli na tri procese: sušenje, desulfurizacijo in rutilizacijo. Diplomsko delo je osredotočeno na prva dva procesa, ki močno vplivata tudi na potek rutilizacije. Kot prej omenjeno, procesi potekajo v kalcinatorju, v katerem se temperatura dviga z dolžino peči in na koncu peči doseže temperature tudi do 1200 °C. Prvi proces je sušenje, s pomočjo katerega poteka eliminacija vode iz vzorcev. Eliminacija poteka v dveh intervalih: v prvem prihaja do izhlapevanja površinske vode, v drugem pa do izhlapevanja porne vode, ki poteka pri višjih temperaturah. Drugi proces je desulfurizacija, s katero se iz vzorca eliminira žveplov dioksid. Tudi ta proces poteka v dveh intervalih. Prvi zajema izhlapevanje prosto vezane žveplove kisline. Tu se eliminirajo še zadnji ostanki vode, hkrati pa zaradi visoke temperature pride do pretvorbe žveplovega trioksida v žveplov dioksid. V drugem intervalu prihaja do razpada sulfatnih mostičkov v sušenem vzorcu, kar sproži potek rutilizacije. S pomočjo podatkov, pridobljenih iz termičnih analiz (te podatke je predhodno pridobil in obdelal Tilen Kopač), sem določil temperaturne intervale za procesa sušenja in desulfurizacije. Na podlagi določitve temperaturnih intervalov sem izračunal pripadajoče aktivacijske energije za oba procesa pri različnih vzorcih. Podatke sem obdelal z neizotermno/izokonverzijsko metodo. Na podlagi primerjave rezultatov različnih vzorcev hidratiziranega titanovega dioksida lahko sklepam, da sem metodo pravilno uporabil in da so dobljeni rezultati natančni. Rezultati diplomskega dela bodo pripomogli k optimizaciji procesov kalcinacije, in sicer k optimalnemu uravnavanju temperatur po dolžini peči za boljši izkoristek in k manjši porabi energije za dosego tako visokih temperatur.

• Language: Slovenian
• Keywords: titanov dioksid, kalcinacija, sušenje, desulfurizacija, neizotermna metoda
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2020
• PID: 20.500.12556/RUL-115191
• COBISS.SI-ID: 1538568643
• Publication date in RUL: 16.04.2020

Secondary language

• Language: English
• Title: Preparation of white pigment from hydrated titanium oxide

Abstract

The present diploma thesis presents processes, which take place in a rotary kiln during the calcination of industrial samples of hydrated titanium dioxide. These samples were made by the sulphate process and were taken from Cinkarna Celje company for thermal analysis. Calcination is divided into three sub-processes: drying, desulfurization and rutilization. This thesis focuses on the first two processes, which strongly influence the course of rutilization. As mentioned, the calcination process takes place in a rotary kiln, where the temperature rises along the length of the kiln and at the very end can reach temperatures as high as 1200 °C. The first sub-process is drying, which eliminates water from the samples. The elimination of water occurs in two intervals: during the first interval the evaporation of surface water takes place and the second interval is the evaporation of water from the pores of the material. The latter occurs at higher temperatures. The second sub-process is called the desulfurization, where sulphur dioxide is eliminated from the sample and it also occurs in two intervals. The first one involves the evaporation of free sulfuric acid. This eliminates the last residual water and at the same time, due to the high temperature, causes the conversion from sulphur trioxide to sulphur dioxide. During the second interval the sulphate bridges start to decompose which triggers also rutilization. With the help of data obtained from thermal analysis (which was previously done by Tilen Kopač), I determined the temperature intervals for both drying and the desulfurization processes. Based on this determination, I calculated the corresponding activation energies for both processes for various samples. Corresponding calculations were done by data processing using the non-isothermal/isoconversial method. Based on critical review of the obtained results I can conclude that the method was used correctly, and the numbers obtained are accurate. The results from diploma thesis will help optimizing the calcination process, namely the optimization and temperature control along the length of the kiln for better process efficiency and lower energy consumption to achieve such high temperatures.

• Keywords: titanium dioxide, calcination, drying, desulfurization, non-isothermal conversion