Xử lý tái chế bùn đỏ từ ngành công nghiệp luyện nhôm. Công trình được nghiên cứu kết hợp giữa công ty Hiệp Phú và trường Đại Học Bách Khoa TP HCM. Công trình được trình bày tại hội nghị quốc tế NOCMAT ở Canada năm 2015.
DEVELOPMENT OF FIBRE CEMENT USING ADDITIVE RED MUD KIEN Pham Trung1,a, HIEP Pham The2,b and NGUYEN Nguyen Cong2,c Faculty of Materials Technology, Ho Chi Minh City University of Technology (HCMUT), Vietnam National University-Ho Chi Minh City (VNU-HCM), Vietnam R&D Department, Hiep Phu Corporation, Vietnam a phamtrungkien@hcmut.edu.vn , b Hiep.pt@hiepphu.com.vn , c nguyen.nc@hiepphu.com.vn Keywords: Red mud, kaolinite, waste treatment, hydrothermal, fiber cement Abstract This research paper presents the feasibility to use Vietnam Red mud (RM) compared with kaolinite as source of starting materials to produce the fiber cement By mixing different ratio of kaolinte (0; 2.5; wt.%)-formulas are using in Hiep Phu Corporation and RM (0; 2.5; 5; wt.%), we can control the physical property of fiber cement sheet XRD and SEM data show that the new crystal appear interlock together to form the mechanical property of fiber cement These fiber cement with high bending strength can be used for construction materials Introduction Red mud (RM) is a wasted product during the Alumina production using Bayer process The red mud has caused to severe environmental problem in many industry countries The chemical and phase composition of RM varies and depend on the source of bauxite as well as the parameter of process operated Basically, chemical composition of RM is composed of 14 to 21 elements, depend on source of RM such as hemactite (Fe2O3), Natri silica aluminate, Ferrite titanate, Alumina monohydrate (Al2O3.H2O), Alumina trihydrate (Al2O3.3H2O), SiO2, TiO2, Na2O, CaO and trace element of rare metal such as V, Ga, Cr, P, Mn, Cu, Cd, Ni, Zn, Pb, Mg, Zr, Hf, Nb, U, Th, K, Ba, and Sr In the last century, many countries (France, Great Britain, Jamaica, Japanese, Italia, USA) dumped RM slurry directly into the sea as the solution for RM treatment [1] This method was harmful and created the alkaline environment and fine particles’ suspension in the sea[1-4] There are nearly million tons of RM waste accumulated at an alumina plant in Turkey between 1973 and 1966 It’s estimated that over 66 million tons of this waste is impounded annually in the world [3] Particular in Vietnam, there are big Alumina factories located in Tan Rai and Nhan Co (Lam Dong province, Vietnam) with the capacity around 2.000.000 metric ton of bauxite/year to produce around 650.000 metric ton of alumina/year, so as factories release around 1.1 metric ton of RM/year The huge amount of RM is still putting severe duty for researcher and management level in Vietnam In order to solve the problems, there are many researches on recycle RM such as ceramic brick, clay brick, Geopolymer brick, catalyst, unfired materials, pigment [5-10] etc., however there is no research on using RM as raw materials for fiber cement It needs to emphasized that the use of fiber cement sheet is increasing yearly around the world In this research, the effect of kaolinite and RM on fiber cement sheet was studied and compared, as well as the feasibility to form 11A tobermorite using Kaolinite and RM Materials & Methods Materials: in this research RM is provided from Tan Rai Alumina factory (Lam Dong province, Vietnam), Kaolinite is provided from Binh Phuoc Kaolin factory (Binh Phuoc province, Vietnam), sand is milled at Hiep Phuoc Co Ltd (Long An province, Vietnam) and PCB 50 cement (Nghi Son, Co Ltd, Vietnam) with the phase composition as follow C3S : 36-39 %; C2S : 30-33%; C3A : 5-7% and C4AF: 8-10% (these data given by Nghi Son Co Ltd Factory) The chemical composition of RM, Kaolinite, Milling sand and PCB 50 cement is analyzed using X-Ray Fluorescence (XRF) (Mesa-50, HORIBA, Japan) The raw materials are mixed with pulp solution (solid ratio of 30%) using different amount of RM and Kaolinite to investigate the suitable formula (as shown in Table 1) Table 1: The mix code of different RM and Kaolinite used in this experiment Number Mix code K0-RM0 K2.5 K5 RM2.5 RM5 RM7 Kaolinite (wt.%) 2.5 0 RM (wt %) 0 2.5 PCB 50 Cement (wt.%) 45 42.5 40 42.5 40 38 Sand (wt.%) 46.5 46.5 46.5 46.5 46.5 46.5 Pulp (wt.%) 8.5 8.5 8.5 8.5 8.5 8.5 The wet mixture is pressed and vacuumed using hydraulic-laminate pressing (8 MPa) to form the laminate sheet with the size 310mm x 150mm x 8mm (as shown in Figure 1) The moisture of fiber cement sample after vacuumed is around 40-45%, and after hydraulic pressing is around 24-28% Fig.1 The vacuumed system (Left) and hydraulic pressing machine (right) to form the fiber cement sheet The fiber cement sheets after forming are treated with hydrothermal using autoclave at 180 oC (9 atmosphere) for 16 hours The fiber cement sheets after hydrothermal treatment are tested using ASTM C1185 standard with the bending strength, moisture content, moisture movement, water absortion, and density In addition, the sample also characterize using X-ray diffraction (XRD) analysis The powder XRD patterns of cement fiber sheet were recorded with a vertically mounted diffractometer system (Bruker-AXS: D8 ADVANCE, Germany) using Ni filtered CuKa generated at 15 kV The morphology of cement fiber sheet were observed using a scanning electron microscope (SEM) (JSM 5400LV, JEOL Co Ltd., Japan) under an accelerating voltage of 20 kV after being coated with gold Results and discussion Table shows the chemical composition of RM, Kaolinite, sand and PCB 50 cement used as raw materials Table 2: Chemical compositions of raw materials (wt.%) Elements RM Kaolinite Milling Sand SiO2 8.37 47.2 97.4 Al2O3 29.91 36.24 0.14 Fe2O3 41.32 0.98 1.16 CaO 0.8 0.1 0.3 MgO 0.41 0.2 TiO2 6.38 0.8 0.154 Na2O+ K2O 3.57 1.7 0.2 LOI 8.98 12.26 0.3 PCB 50 cement 21.18 4.57 3.03 59.23 Table shows the physical property (pH, size of particle, density) of RM, Kaolinite, sand and cement PCB 50 used as raw materials Table 3: Physical properties of raw materials (wt.%) Elements RM Kaolinite Milling Sand PCB 50 cement pH 11 3.9 12-14 Size of particle (cm /g) 6000 17000 3200 3000 Density (g/cm ) 3.01 2.4 2.7 3.05 Figure shows the FTIR spectra of RM, the bonding peak of H-O-H is from 3620-3434 cm -1, and 1639 cm-1; the bonding peak of CO3 is 1477-1410 cm-1; the bonding peak of Si-O-Si, Si-O is 1002 cm-1; the bonding peak of Al-O-H is 802cm-1 and the bonding peak of Si-O, Si-O-Fe is 455 cm1 These data concluded that the chemical composition of RM is Alumina, Iron and Silicon as stated in Table Fig.2 FTIR spectra of RM Figure shows XRD spectra of RM RM have non-crystallite ground and major morphology structure of Al in RM is gibbsite (it’s effective structure for additive using in autoclaved fiber cement).[11] Fig.3 XRD spectra of RM Figure shows the XRD spectra of fiber cement sheet using different amount of RM and kaolinite hydrothermal treatment at 180 oC for 16 hours The tobermorite can be formed only when using red mud with the amount up 5wt.% Fig.4 XRD patterns of fiber cement sheet using different amount of Kaolinite and RM (A) different amount of kaolinite used (0 wt.%; 2.5 wt.% and wt%) (B) different amount of RM used (0 wt.%; 2.5 wt.%; wt.% and wt.%) Legend: Q – Quartz; T – 11Ao Tobermorite Figure shows morphology of fiber cement sheet using different amount of RM and kaolinite hydrothermal treatment at 180oC for 16 hours Fig.5 SEM morphology of fiber cement sheet using different amount of Kaolinite and RM (A) different amount of kaolinite used (0 wt.%; 2.5 wt.% and wt%) (B) different amount of RM used (0 wt.%; 2.5 wt.%; wt.% and wt.%) Figure shows clearly shapes of RM particles in fiber cement RM particles have globural shape with diameter 1-2µm C-S-H crystalline on the surface of RM demonstrate that there were reactions between elements in RM with the elements in formula such as cement and SiO Specially reactions between Al (major Gibbsite morphology stucture in RM) with CaO and SiO2 (in cement and SiO2) [11] Fig.6 SEM morphology of RM particles in fiber cement sheet Formulation: RM (5wt.%, 7wt.%) Figure show the physical property of fiber cement sheet, when we add kaolinite and RM the bending strength also decrease (Fig 5A), and increase the bulk density (Fig 5B), also decrease the water absorption in case of adding RM (Fig 5C) however the moisture movement show no significant change in RM used (2.5wt.%; 5wt.%) and decrease in RM 7wt.% (Fig 5D) Fig 7: Physical property of fiber cement sheet depend on the amount of kaolinite and RM used (A) Bending strength; (B) Bulk density; (C) Water absorption and (D) Moisture movement The meaning of this research need to put in the context of our facility and current RM research in Vietnam As mention in the introduction, RM is cause the big problem for environment, since they contain large of Iron and alumina By using RM and kaolinite as starting materials, the Hiep Phu Ltd Company succeed to produce fiber cement with higher density and lower water absorption, although the bending strength is slightly reduce, but still satisfy the ASTM C1186 standard Conclusions Our research group presents the feasibility to use Vietnam Red mud (RM) could replace kaolinite as source of starting materials to produce the fiber cement By mixing different ratio of RM (0; 2.5; 5; wt.%), we can control the physical property of fiber cement sheet These RM-fiber cement might be a future applications for construction materials and play an important role to eliminate the storage of the RM in Viet Nam Acknowledgement The research group acknowledge Hiep Phu Ltd Corporation sponsor for this project References [1] Dethlefsen Volkert, Rosenthal Harald Problems with dumping of redmud in shallow waters, A critic review of selected literature Aquaculture 1973;2:267–80 [2] Basden S Environmental study of disposal of red mud waste Mar Pollut Bull 1976;7:4–7 [3] Agrawal A, Sahu KK, Pandy BD Solid waste management in non-ferrous industries in India Resources Conserv Recycl 2004;42:99–120 [4]Sglavo Vincenzo M, Campostrini Renzo, Maurina Stefano, Carturan Giovani, Monagheddu Mario Bauxite ‘red mud’ in the ceramic industry Part I:thermal behavior.J Eur Ceram Soc 200;20:235-44 [5]Singh Maneesh, Upadhayay SN, Prasad PM Preparation of special cements form red mud Waste manage 1996;8:665-70 [6]Kavas Taner Use of boron waste as a fluxing agent in production of red mud brick Build Environ 2006;41:1779-83 [7]Synthesis and Characterization of Geopolymer for Infrastrctural applications – Jian He [8]Ordonez S, Sastre H, Diez FV Catalytic hydrodechlorination of tetrachloroeethylene over red mud J Hazard Mater 2001; B81:103-14 [9]Jiakuan Yang, Bo Xiao Development of unsintered construction materials from red mud wastes produced in the sintering alumina process 2007 [10]Pera J, Boumaza R, Ambroise J Development of a pozzolanic pigment from red mud Cement Concrete Res 1997;27:1513–22 [11] A M Cooke and S A S Akers, The effect of aluminous additives on the properties of Autoclaved Cellulose Fibre Cement IIBCC 2008 19 ... effective structure for additive using in autoclaved fiber cement) .[11] Fig.3 XRD spectra of RM Figure shows the XRD spectra of fiber cement sheet using different amount of RM and kaolinite hydrothermal... can be formed only when using red mud with the amount up 5wt.% Fig.4 XRD patterns of fiber cement sheet using different amount of Kaolinite and RM (A) different amount of kaolinite used (0 wt.%;... patterns of cement fiber sheet were recorded with a vertically mounted diffractometer system (Bruker-AXS: D8 ADVANCE, Germany) using Ni filtered CuKa generated at 15 kV The morphology of cement fiber