Tallinn University of Technology Granulation of oil shale

Tallinn University of Technology Granulation of oil shale ashes for neutralizing acidic soils Tiit Kaljuvee, Jekaterina Jefimova, Valli Loide, Mai Uibu, Marve Einard, Rein Kuusik Jõhvi, 16 th of November 2017

Layout n Background n Characterization of oil shale ashes n Materials and methods n Results n Conclusions IX Oil Shale Conference, 16 November 2017

Acidification of soil is serious global problem which is caused by: the precipitation from the atmosphere of acidifying gases (SO 2, NH 3, HNO 3, etc. ) n the application of acidifying fertilizes (urea, ammonium salts, etc. ) n n nutrient uptake by crops n the mineralization of organic matter n leaching processes in soil in climatic regions where the evaporation is lower than annual rainfall, etc. IX Oil Shale Conference, 16 November 2017

Acidification of soil in Estonia n n In Estonia the evaporation is about 250 -300 mm lower than the annual average rainfall, and as a result of that, calcium and magnesium compounds are washed out from the upper layers of the soil under the influence of soil filtrating water – leaching of carbonates occurs, and soil becomes acidic and less fertile. In Estonia there is 350 000 ha of agricultural land that needs permanent annual liming. IX Oil Shale Conference, 16 November 2017

Neutralization (liming) of acidic soil Materials used in liming: limestone - Ca. CO 3, burnt lime - Ca. O, slaked lime - Ca(OH)2 dolomite – Ca. Mg(CO 3)2 gypsum - Ca. SO 4*2 H 2 O coal fly ash - Ca. O, Ca. Si. O 3, etc. wood (peat) ash - Ca. O, K 2 O, etc. oil shale ash – Ca. O, Ca. CO 3, Ca. Si. O 3, Mg. O, etc. IX Oil Shale Conference, 16 November 2017

Oil shale consumption in Estonia in 2016*: n ~13. 1 million tons: n ~73% in electricity production n ~27% in the production of shale oil and heat Electricity production in 2016: n n ~9 100 GWh, from which ~90% was produced by Eesti Energia in its power plants: Estonian Power Plant Auvere Power Plant Baltic Power Plant *Estonian Oil Shale Industry, Yearbook 2016 IX Oil Shale Conference, 16 November 2017

Oil shale combustion technologies Pulverized firing (PF): n t - 1200 - 1400°C n Kcarbonates decomposition - ~0. 97 n Ksulphur binding - 0. 75 – 0. 85 Circulating fluidized bed combustion (CFBC): n t - 750 - 820°C n Kcarbonates decomposition - 0. 75 – 0. 85 n Ksulphur binding - ~1 IX Oil Shale Conference, 16 November 2017

Oil shale ashes formed at combustion of oil shale differ from each other by the: § § § chemical composition phase composition grain-size composition morphology physical and chemical characteristics CFBC ashes PF ashes CFBC/BA Bottom ash PF/BA Bottom ash CFBC/INT Intrex ash PF/SHA Superheater ash CFBC/ECO Economizer ash PF/ECO Economizer ash CFBC/PHA Air preheater ash PF/CA/NID Cyclone ash/De. SOx ash CFBC/ESPA 1 and 4 Electrostatic PF/ESPA precipitator ash, fields 1 and 3 1 st and 4 th IX Oil Shale Conference, 16 November 2017 Electrostatic precipitator ash, fields 1 st and 3 rd

The aim of this work was to study the possibilities of granulation of OS ashes for obtaining granulated products suitable for their use in liming of acidic soils. Experiments were focused on three important parameters which are mostly considered in the case of fertilizers: - particle size, - compressive strength, - leachability of components. IX Oil Shale Conference, 16 November 2017

Chemical composition (%) Item Sample/Content, % PF/CA PF/ De. SOx CFBC/ MIX CFBC/ ESPA, I field Clay Ca. Ototal 51. 6 36. 3 38. 3 28. 3 0. 8 Ca. Ofree 20. 9 7. 9 9. 5 9. 1 - Mg. O 3. 3 4. 7 4. 1 4. 3 2. 5 CO 2 1. 2 3. 7 11. 5 4. 6 0. 2 Si. O 2 24. 5 28. 5 23. 8 38. 4 58. 7 Al 2 O 3 6. 4 7. 3 6. 1 10. 3 17. 7 Fe 2 O 3 3. 9 3. 6 3. 3 4. 7 6. 8 SO 3 total 5. 1 9. 2 6. 1 5. 8 0. 7 K 2 O 2. 0 3. 6 3. 2 4. 6 6. 2 BET SSA, m 2 g-1 0. 91 1. 43 3. 78 3. 69 40. 53 Porosity, mm 3 g-1 1. 67 3. 84 7. 20 11. 36 59. 95 dmean, mm 55. 8 49. 6 48. 1 32. 5 15. 1 IX Oil Shale Conference, 16 November 2017

Phase composition (%) PF/ CFBC/ CA De. SOx MIX ESPA, 1 field ▪ Lime, Ca. O 28. 3 13. 2 11. 0 12. 6 n Calcite, Ca. CO 3 3. 3 11. 4 22. 3 10. 5 n Anhydrite, Ca. SO 4 8. 6 17. 7 11. 6 9. 4 n Quarz, Si. O 2 4. 4 9. 0 14. 1 20. 2 n Orthoclase, KAl. Si 3 O 8 3. 9 2. 9 10. 5 15. 4 n Wollastonite, Ca. Si. O 3 3. 7 - 1. 0 0. 9 n Belite, Ca 2 Si. O 4 24. 0 19. 3 6. 1 7. 4 n Merwinite, Ca 3 Mg(Si. O 4)2 6. 3 3. 6 1. 5 0. 8 n Melilite, (Ca, Na)2(Mg, Al)Si. Al)3 O 7 8. 2 2. 0 2. 3 1. 7 n Periclase, Mg. O 5. 1 4. 2 3. 0 2. 5 IX Oil Shale Conference, 16 November 2017

Morphology CFBC/ESPA, 1 field PF/CA • CFBC ashes are characterized by irregular shape and porous and uneven surface. The glassy phase is not formed. • PF ashes are characterized by regular spherical shape with smooth surface. The glassy phase significantly affects the formation of particle shape and surface properties. IX Oil Shale Conference, 16 November 2017

Methods n n n Laboratory plate granulators (d = 0. 55 m and 1. 4 m) and EIRICH mixer-type granulator were used for granulation, and Bonnot 2. 25’’ extruder was used for pelletizing of oil shale ashes. Clay and clinker dust (10%) were used as solid binding additives. Liquid binders: ash transportation water (TW), water glass (WG), black liquor (BL), lignosulphonate (LS), polyacrylamide (PAA), carbonylmethylcellulose (CMC), etc. Different storing and drying regimes for treatment of green granules were used: - dried at 105°C or at 60°C, - stored hermetically closed ( HC), - stored/dried in open air (OA) at room temperature (RT), - stored in the atmosphere of carbon dioxide (CO 2). n IX Oil Shale Conference, 16 November 2017

Methods n For determination of leachability of ash components the granulated products, and, for comparison, origin ashes were tested using laboratory lysimetries. Granulated as well as non-granulated ashes were mixed in the upper part (1/3 level) of Gleyic Podzoluvisol soil (p. H=4. 7) with stoutness of 0. 25 m. The mass of samples was calculated on the level of 7. 5 t Ca. CO 3 ha-1 considering the content of calcium in studied samples. The content of moisture in soil was held on the level of 40 -50% considering the saturation ability of soil with moisture. IX Oil Shale Conference, 16 November 2017

Methods n n n n TG-DTA-MS: Setaram Labsys 1600 thermoanalyzer coupled with Pfeiffer Omni. Star Mass Spectrometer. BET SSA and porosity measurements with a Sorptometer Kelvin 1042. FTIR: Bruker ALPHA. The surface observations of the samples were carried out with a scanning electron microscope Jeol JSM-8404. XRF and XRD: Bruker D 8 Advance Diffractometer. Mechanical hardness of granules – Brookfield Texture Analyzer, vibrosieve tests – THYR 1. The content of Ca, Mg, K, and S in leaching solution – AAS Spectra AA, spectrometer Spectro. Direct. IX Oil Shale Conference, 16 November 2017

Plate granulator and its simplified scheme Plate of the granulator Trajectory of granules IX Oil Shale Conference, 16 November 2017

EIRICH Mixers: EL 1 (and RV 01) Maschinenfabrik Gustav Eirich Gmb. H & Co KG IX Oil Shale Conference, 16 November 2017

The Bonnet Company 21/4'' laboratory extruder IX Oil Shale Conference, 16 November 2017

Results obtained using laboratory plate granulators IX Oil Shale Conference, 16 November 2017

Mean fractional composition (%) of granulated ashes Diameter >5 4 -5 Sample mm mm 3 -4 mm 2 -3 mm 1 -2 mm 0 -1 mm PF/CA 6. 8 5. 6 10. 2 38. 2 34. 1 5. 1 PF/De. SOx 8. 6 9. 7 13. 1 23. 9 38. 4 6. 3 CFBC/MIX 7. 1 6. 7 11. 8 33. 8 36. 3 4. 3 CFBC/ESPA 7. 2 7. 1 14. 3 36. 3 30. 9 4. 2 IX Oil Shale Conference, 16 November 2017

Compressive strength of granules (d =3 -4 mm) with 10% of clay granulated with TW IX Oil Shale Conference, 16 November 2017

Compressive strength of granules (d=3 -4 mm) with 10% of clay granulated with different binders IX Oil Shale Conference, 16 November 2017

Compressive strength of granules (d=3 -4 mm) with 10% of clay granulated with TW IX Oil Shale Conference, 16 November 2017

Investigation of the granulation mechanism IX Oil Shale Conference, 16 November 2017

The content of free Ca. O in the ashes causes in contact with water, especially at HC storing of granules, the reaction of free Ca. O and water with the formation of calcium hydroxide: Ca. O + H 2 O = Ca(OH)2 When the granules are dried at RT or green granules are stored in OA the calcium hydroxide reacts with carbon dioxide contained in air with the formation of calcium carbonate increasing the final strength of granules via forming mineral binding bridges between the particles in granule: Ca(OH)2 + CO 2 = Ca. CO 3 + H 2 O IX Oil Shale Conference, 16 November 2017

TG curves for CA+10% clay composition with different post-granulation treatment IX Oil Shale Conference, 16 November 2017

DTG curves for CA+10% clay composition with different post-granulation treatment IX Oil Shale Conference, 16 November 2017

Emission profiles of H 2 O and CO 2 emitted at thermal treatment of CA+10% clay +TW : 24 h HC, 60°C (blue lines) and 24 h HC+48 h OA (red lines) IX Oil Shale Conference, 16 November 2017

Transmittance, % FTIR spectra of granulated samples with different post-granulation treatment in the wavenumber region characteristic to OH- Wavenumber, cm-1 IX Oil Shale Conference, 16 November 2017

Transmittance, % FTIR spectra of granulated samples with different post-granulation treatment in the wavenumber region characteristic to CO 3 -2 Wavenumber, cm-1 IX Oil Shale Conference, 16 November 2017

Compressive strength of granules (3 -4 mm) with 10% of clay granulated with TW and stored in the atmosphere contained 15% of CO 2 IX Oil Shale Conference, 16 November 2017

TG curves of ESPA+10% clay composition stored in CO 2 atmosphere (15%) IX Oil Shale Conference, 16 November 2017

DTG curves of ESPA+10% clay+TW (m=15 mg, heating rate 10° min-1, 79%Ar+21%O 2) IX Oil Shale Conference, 16 November 2017

Emission profiles of H 2 O and CO 2 for ESPA+10% clay+TW IX Oil Shale Conference, 16 November 2017

Compressive strength of granules (d=3 -4 mm) with 10% clay granulated with TW and with different post-treatment of green granules (diameter of plate granulator d = 1. 4 m) IX Oil Shale Conference, 16 November 2017

Interim conclusions n n n It has been shown that the most voluminous kinds of OS ashes (CFBC/MIX, ESPA I, PF/CA and De. SOx) can be granulated and a success of the process depends on the number of ash characteristics and process parameters. The results obtained showed that the compressive strength of granules is strongly dependent on reactions occurring during granule formation and their following drying. Using different solid binding additives and liquid binders as well as different drying regimes makes it possible to obtain granules resistant to compressive strength of 5 -20 N per granule. At that 85% of the produced granules had a diameter of 1 -5 mm and 70 -75% of these a diameter of 1 -3 mm. IX Oil Shale Conference, 16 November 2017

Physical structure of granules IX Oil Shale Conference, 16 November 2017

Morphology of granules PF/CA+10% clay+TW CFBC/ESPA I+10% clay+TW The dependence of granules porosity and packing density on the ash used is well seen in SEM pictures: the granules of ESPA are more compact and have less bigger voids as compared to granules made with CA. IX Oil Shale Conference, 16 November 2017

Specific surface area and porosity of samples (d=3 -4 mm) granulated with TW IX Oil Shale Conference, 16 November 2017

Pore size distribution of samples stored in the atmoshere of CO 2 (15%) 6. 0 E-01 5. 0 E-01 ESPA+10%clay+TW_60°C 24 h -d. V/d(logd), [cc/g] 4. 0 E-01 ESPA+10%clay+TW_CO 2 4 h 3. 0 E-01 ESPA+10%clay+TW_CO 2 8 h ESPA+10%clay+TW_CO 2 2 h 4 2. 0 E-01 1. 0 E+04 1. 0 E+03 1. 0 E+02 1. 0 E+01 1. 0 E+00 Pore diameter, [µm] 1. 0 E-01 IX Oil Shale Conference, 16 November 2017 1. 0 E-02 0. 0 E+00 1. 0 E-03

Relationship between compressive strength and SSA and porosity of granules stored in the atmoshere of CO 2 (15%) IX Oil Shale Conference, 16 November 2017

Lysimetric tests n The filtrates were collected on the 2 nd, 8 th and 22 nd week after starting the test. The content of Ca 2+, Mg 2+, K+ and SO 42 - was establised in filtrates. Before and after the test the soil was analyzed on the content of available calcium, magnesium, potassium and sulphate ions, and p. HKCl value were also determined. IX Oil Shale Conference, 16 November 2017

Content of Ca 2+ in filtrates collected at different time after starting the lysimetric test (ash+10% clay+TW) IX Oil Shale Conference, 16 November 2017

Content of SO 42 - in lysimetric filtrates collected at different time after starting the lysimetric test (ash+10% clay+TW) IX Oil Shale Conference, 16 November 2017

Sum of leached ions (mg L-1) and the influence (%) of granulation on it n IX Oil Shale Conference, 16 November 2017

p. H value and content of available ions in soil (mg kg-1) and the influence of granulation on it Sample p. HKCl Ca 2+ Mg 2+ K+ SO 42 - Before After mg kg-1/% Control CA, fine 4. 7 4. 5 6. 4 624/1886/100 37/129/100 146/157/100 11. 3/- 68. 8/100 CA, gran_24 h 60°C CA, gran_24 h CO 2 ESPA, fine 6. 5 1951/104 132/102 159/102 67. 0/ 97 6. 3 1770/ 94 115/ 89 170/107 41. 3/ 60 5. 8 1342/100 126/100 198/100 74. 5/100 ESPA, gran_24 h 60°C ESPA, gran_24 h CO 2 5. 8 1287/ 96 111/ 88 183/ 92 75. 0/101 5. 8 1245/ 93 114/ 90 184/ 93 61. 5 /83 IX Oil Shale Conference, 16 November 2017

Conclusions n n n The main technologigal parameters for granulation of the most voluminous kinds of OS ashes (CFBC/MIX, ESPA I, PF/CA and De. SOx) using plate and Eirich-type granulators have been worked out. They are ready for future control and development at large scale demonstration equipment. The mechanism of formation of OS ash granules and main parameters influencing on it has been elaborated. Granulation allowes to enrich the granulated products with different nutrients required for normal growth of plants. IX Oil Shale Conference, 16 November 2017

Conclusions n The results of lysimetric test indicated that using of granulated OS ashes have several advantages comparing with fine ashes: - granulation of ashes gives a real chance to regulate and control the speed of leaching of ash components into soil, - the soil neutralizing ability of granulated products is prolonged (extended) allowing to lime acidic soils more seldom being at that more effective comparing with fine ashes, - the transportation, handling and uniformity of spreading using granulated ashes is improved, - the loss of ions with probable contamination of subsoil water and water-bodies is also diminished. IX Oil Shale Conference, 16 November 2017

Tänan! Thank you very much! IX Oil Shale Conference, 16 November 2017