Study of Thermooxidation of Oil Shale Samples and Basics of Processes for Utilization of Oil Shale Ashes

Tiit Kaljuvee,Can Rüstü Yörük,Olev Trass,Valli Loide,Tomáš Húlan,Mai Uibu,Igor Štubňa,Rein Kuusik,Andres Trikkel,Jekaterina Jefimova,Marve Einard

doi:10.3390/min11020193

Abstract

A circular economy becomes an object of actual discussions as a real alternative to the existing linear economy system. The problem is actually in Estonia also, first of all in the sector of heat and power production which based mainly on the combustion of local solid fossil fuel—Estonian oil shale (OS) resulting in the formation of ~5–6 million tons of OS ashes annually. The thermooxidative decomposition of OS samples from different deposits and estimation of the possibilities of utilization of OS ashes formed at both—pulverized firing (PF) and circulating fluidized bed combustion (CFBC) of Estonian OS were studied. The thermal analysis combined with evolved gas analysis (EGA) methods like Fourier transform infrared (FTIR) and mass-spectroscopy (MS) was exploited. It was established that the differences in the thermal behaviour of different OS samples are caused by the differences in the chemical matrix of organic matter, chemical and mineralogical composition of the inorganic part of OS, and morphology of samples. It was also found that moderate grinding of OS ashes with simultaneous moderate water treatment notably improved the SO2 binding efficiency of cyclone ash, and that the strength and leachability characteristics of granulated OS ashes strongly depend on the post-granulation treatment conditions allowing to increase the soil neutralizing ability of the granulated products. This overview was based on our investigations carried out during the last fifteen years.

Highlights

Over the last decade, increasing attention was paid to the circular economy as an alternative to the existing linear economy system which is based on continuous growth and increasing resource throughput [1,2,3,4,5,6]
Around 10 million tons of oil shale (OS) was used in heat and power production and ~5–6 million tons of OS ashes was formed in Estonia in
The results obtained will serve in the future optimization of technological parameters for the utilization of oil shale ashes

Summary

Introduction

Over the last decade, increasing attention was paid to the circular economy as an alternative to the existing linear economy system which is based on continuous growth and increasing resource throughput [1,2,3,4,5,6]. The importance of re-use of wastes and utilization of by-products has been realized. There is a new strategic interest in Estonia, especially in the heat and power production industry. 70% of the energy production in Estonia is based on the combustion of Estonian OS containing organic matter on the level of only 30–35%. Around 10 million tons of OS was used in heat and power production and ~5–6 million tons of OS ashes was formed in Estonia in

Methods

Results

Conclusion