PHYSICO-CHEMICAL AND RADIOLOGICAL CHARACTERIZATION OF PHOSPHOGYPSUM FOR ITS VALORISATION IN CEMENT MORTAR

Transcription

1 5th International Conference on Sustainable Solid Waste Management, Athens, June 2017 ATHENS2017 PHYSICO-CHEMICAL AND RADIOLOGICAL CHARACTERIZATION OF PHOSPHOGYPSUM FOR ITS VALORISATION IN CEMENT MORTAR S.M. Pérez-Moreno, J. Rosales, M. Cabrera, F. Mosqueda, M.J. Gázquez, F. Agrela, J.P. Bolivar Group of Radiations Physics and Environment (FRYMA) University of Huelva, Huelva, Spain. 1

2 INTRODUCTION PHOSPHOGYPSUM STACK: OVER 100 Mt 1000 ha. Ca10(PO4)6F2+ 10 H2SO4 6 H3PO CaSO4 2H2O + 2HF SPAIN HUELVA PHOSPHORIC ACID INDUSTRY June

3 INTRODUCTION NORM (NATURALLY OCCURRING RADIOACTIVE MATERIAL) Ca 10 (PO 4 ) 6 F H 2 SO 4 6 H 3 PO CaSO 4 2H 2 O + 2HF (1.66 kg of PG per kg of treated P) Pb-Ra > 90% PG (Bq/kg) Series 238 U 232 Th 40 K Phosphorite (Bq Kg -1 ) 1500 <20 <30 Phosphorite Th ~ 70% Phosphogypsum 234 U 55 ± Th 466 ± 51 Typical Soil (Bq Kg -1 ) U < 20% 226 Ra 693 ± Pb 771 ± 29 Secular equilibrium in Phosphorite (same activity concentration for all radionuclides): 3

4 OBJECTIVES APPLICATION OF PHOSPHOGYPSUM IN CIVIL ENGINEERING The main objective is to use the Phosphogypsum as Setting Retarders to replace the natural gypsum in Cement Mortar. Physico-chemical and Radiological Characterization of Mortars and their Raw Materials, and their Environmental Implications 4

5 MATERIALS AND METHODS RAW MATERIALS: PHOSPHOGYPSUM (PG) NATURAL GYPSUM (NG) CLINKER (CK) NORMALIZED SAND (S) CEMENT MORTARS: Curing conditions: 20 ºC,100% humidity C-OPC-M PG-M NG/PG-M CK (wt%) S (wt%) NG (wt%) PG (wt%) W (wt%) ADITIVE (wt%)

6 MATERIALS AND METHODS CHARACTERIZATION METHODS: X RAY FLUORESCENCE (XRF) X RAY DIFFRACTION (XRD) ICP-MS/OES GRANULOMETRY ANALISYS ELECTRONIC MICROSCOPY (SEM-EDS) GAMMA SPECTROMETRY ANALYSIS LIXIVIATION TEST (UNE-EN ) 6

7 RESULTS: XRF Al Ca Cu F Fe RAW MATERIALS K Mg NG ND ND ND PG ND ND ND ND ND 0.22 ND CK ND S ND ND ND Mn Ni P Pb S Si P.C. Al Ca Cu F CEMENT MORTARS Fe K Mg C-OPC ND NG-M ND ND PG-M ND ND Mn Ni P Pb S Si P.C. NG/PG-M ND ND

8 RESULTS: XRD (RAW MATERIALS) PG NG Gypsum (CaSO 4 2H 2 O) Bassanite (CaSO 4 1/2H 2 O) n.d 1.5 Anhydrite (CaSO 4 ) n.d <1 Dolomite (CaMg(CO 3 ) 2 n.d 5.6 Magnetite (Fe 2 O 3 ) n.d <1 Chukhrovite <1 n.d (Ca 4 AlSi(SO 4 )F 13 12(H 2 O)) Quartz (SiO 2 ) <1 <1 CK Alite (Ca 3 SiO 5 ) (C3S) 66 Larnite (Ca 3 SiO 4 ) (C2S) 9.3 Brownmillerite 8.4 (AlCa 2 FeO 5 ) (C2AF) Al 2 Ca 4 Fe 2 O 10 (C4AF) 6.1 Al 2 Ca 3 O 6 (C3A) 3.1 Fayalite (Fe 2 SiO 4 ) 2.3 Portlandite (Ca(OH) 2 ) 3.3 Lime (CaO) 1.7 S Quartz (SiO 2 ) 100 8

9 RESULTS: GRANULOMETRY ANALYSIS RAW MATERIALS 10 S Clay:<4µm Silt: 4 62 µm Sand: µm Gravel: > 2000 µm VOLUME CK PG NG 0-2 0, Particle Size (µm) PG NG CK S 9

10 RESULTS: SEM-EDS (RAW MATERIALS) PG 1 CaSO 4 2H 2 O CaSO 4 2H 2 O NG

11 RESULTS: SEM-EDS (RAW MATERIALS) CK 4 AlCa2FeO5 (C2AF) S SiO Ca3SiO5 (C3S) 5 11

12 RESULTS: MORTARS MAIN REACTIONS DURING CURING OF MORTARS: Tri- calcium silicates (C3S) 2(CaO) 3 (SiO 2 ) + 7H 2 O (CaO) 3 (SiO 2 ) 4(H 2 O) + 3Ca(OH) 2 AMORFOUS (C-S-H) PORTLANDITE Di- calcium silicates (C2S) 2(CaO) 2 (SiO 2 ) + 5H 2 O (CaO) 3 (SiO 2 ) 4(H 2 O) + Ca(OH) 2 AMORFOUS (C-S-H) PORTLANDITE Calcium aluminate (C3A) in presence of gypsum (CaO) 3 (Al 2 O 3 ) + 3 CaSO 4 2(H 2 O) + 26 H 2 O (CaO) 3 (Al 2 O 3 )(CaSO 4 ) 3 32(H 2 O) Ettringite 12

13 RESULTS: XRD MORTARS C-OPC-M PG-M NG/PG-M Quartz (SiO 2 ) Portlandite (Ca(OH) 2 ) Ettringite (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 26(H 2 O) Brownmillerite (AlCa 2 FeO 5 ) (C2AF) Alite (Ca 3 SiO 5 ) (C3S) Calcite (CaCO 3 )

14 RESULTS: SEM-EDS MORTARS C-OPC-M PG-M C3S: (CaO) 3 (SiO 2 ) C2S: (CaO) 2 (SiO 2 ) C2AF: (CaO) 2 (Al 2 O 3 )(FeO) 14

15 RESULTS: LIXIVIATION TEST MORTARS R.D. 1481/2001 which regulates the disposal of waste by landfill. LIXIVIATION TEST ACCORDING TO UNE EN NO HAZARDOUS HAZARDOUS C-OPC (mg/kg) PG-M (mg/kg) NG/PG-M (mg/kg) L/S = 10 (mg/kg) L/S = 10 (mg/kg) Cr , Ni <LD , Cu <LD <LD <LD Zn As <LD 0.01 <LD 0, Se <LD <LD <LD 0,1-0,5 0,5-7 Mo , Cd <LD 0.01 <LD 0, Sb ,06-0,7 0,7-5 Ba Hg <LD <LD <LD 0,01-0,2 0,2-2 Pb 0.12 <LD ,

16 RESULTS: MORTARS European Union Regulation: Radiation protection 112 C-OPC PG-M NG/PG-M Bq/kg Bq/kg Bq/kg 234 Th 7.9± ± ± Ra 7.2± ± ± Pb 12.2± ± ± Ra 6.6± ± ± Th 6.6± ± ± K 104±7 123±7 155±11 INDEX I I=( 226 Ra/300)+( 228 Ra/200)+( 40 K/3000) < 1 (materials used in bulk amounts, e.g. concrete) 16

17 FINALS REMARKS This study was carry out to use the phosphogypsum as setting retarders to replace the natural gypsum in cement mortar. Physico-chemical and Radiological Characterization of mortars and their raw materials have been performed. Several mortars have been manufactured by according to regulations of building materials. The composition and mineral phases of mortar cement manufactured of PG are the expected and similar that were found in the control mortar. Lixiviation test and radiological risk index reveal that the mortars do not involve radiological either environmental risks. ACCORDING TO THE RESULTS THERE ARE NOT SIGNIFICANT DIFFERENCES BETWEEN MANUFACTURED MORTARS WITH NG AND PG 17

18 5th International Conference on Sustainable Solid Waste Management, Athens, June 2017 ATHENS2017 THANK YOU FOR YOUR ATTENTION S.M. Pérez-Moreno, J. Rosales, M. Cabrera, F. Mosqueda, M.J. Gázquez, F. Agrela, J.P. Bolivar Group of Radiations Physics and Environment (FRYMA) University of Huelva, Huelva, Spain. 18