Performance of Dolomite Calcination in a Bench-Scale Rotary Kiln

Winny Wulandari,Fadly Junico Juanjaya,Muhammad Faqih Alwi,Subagjo Subagjo,Anggoro Tri Mursito,A.C Kumoro,P.T.S Nam,W.R.W Daud,M.T Phong,A.W Lothongkum,X Rong,Hadiyanto Hadiyanto,L Yung,S.A Roces,M.A Hussain

doi:10.1051/matecconf/201815606008

Abstract

Dolomite calcination is one of process steps to prepare calcined dolomite for raw materials in magnesium production. Calcination of dolomite involves heating the raw material at sufficient temperature in order to release the carbon dioxide from its carbonate minerals. This process is commonly conducted in a rotary kiln. There have been a number of calcination studies in a laboratory scale, but the study of dolomite calcination in a larger scale is very scarce. This research is aimed to study the performance of dolomite calcination in a bench-scale rotary kiln with 500 gram of feed. The effect of various parameters, including temperatures, feed rate, rotating frequency, and particle size were examined. The temperature of rotary kiln was varied between 700 and 1000 °C, while the particle size of dolomite was varied between 0.149 – 0.297 mm and up to 10 – 15 mm. The temperature distribution inside the rotary kiln was also measured. It is obtained that a conversion of 92% was attained at operation temperature of 1000 °C, which is at a higher temperature compared to the laboratory scale, where a conversion of 100% was obtained at 900 °C. This imply that the effect of heat transfer also plays important role in the calcination of dolomite especially at a larger scale.

Highlights

Dolomite, CaCO3.MgCO3, is a mineral found in several places in Indonesia with an estimated reserve of 2,396,707 thousand tons, based on the data from the Ministry of Energy and Mineral Resources in 2010
Dolomite calcination is an important step in the processing of dolomites into other materials of higher value such as fluxes and additives in steel processing smelters, kieserite (MgSO4.H2O) fertilizer, refractory bricks, sulfur dioxide capture medium in Flue Gas Desulfurization (FGD), and as the raw materials for magnesium production
The study on dolomite decomposition in a TGA using nitrogen as the inert atmosphere by the authors [2] showed that decomposition of dolomite is a one step process that began at 700°C and finished at 850 °C with activation energy of 149,5 kJ/mol

Summary

Introduction

CaCO3.MgCO3, is a mineral found in several places in Indonesia with an estimated reserve of 2,396,707 thousand tons, based on the data from the Ministry of Energy and Mineral Resources in 2010. The mechanism is different when dolomite decomposes in atmosphere containing CO2, as it decomposes with two step reactions as in the following: CaMg(CO3)2(s) CaCO3(s) + MgO(s)+CO2(g) (2). The study on dolomite decomposition in a TGA using nitrogen as the inert atmosphere by the authors [2] showed that decomposition of dolomite is a one step process that began at 700°C and finished at 850 °C with activation energy of 149,5 kJ/mol. This study showed that the maximum conversion of dolomite calcination in a laboratory scale tubular furnace is 100%. Study on dolomite decomposition in tubular furnace using atmosphere consisting of air and CO2, as an atmospheric replication in rotary kiln, shows that decomposition of dolomite occurs in two steps, starting at 650°C until 820°C with 162 kJ/mol of activation energy [3]. The maximum conversion of 80 – 90% in this atmosphere was achieved at 900 °C

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