Evaluation of field compaction of a filtered residue from alumina production K.D. Nery UFMG, Brazil

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1 Evaluation of field compaction of a filtered residue from alumina production K.D. Nery UFMG, Brazil L.F.S. Villar UFMG, Brazil R.A. Moreno Companhia Brasileira de Aluminio, Brazil J.P. Freire Neto Pimenta de Ávila Consultoria, Brazil M. Scarmínio Pimenta de Ávila Consultoria, Brazil R.S. Junior Companhia Brasileira de Aluminio, Brazil

2 Introduction TECHNOLOGICAL DEVELOPMENT Growth in ore exploitation; Increasing in generation of tailings and industrial residues; Concern for waste storage systems safety; Stringent environmental laws.

3 Introduction Alumina Industry - Residue disposal solution Envio do rejeito para o filtro prensa Dry Stacking Drum Filter Rejeito após passar pelo filtro prensa Filtered residue Press Filter

4 Introduction Filtered residue Press Filter

5 Introduction Disposal of Filtered Residue: Compact to regain storage volume; To increase shear strength and therefore bearing capacity; To increase stiffness and therefore to reduce future settlement; To decrease voids ratio and hence permeability, which as consequence reduces the infiltration of rainwater.

6 Objective To evaluate the field compactability of a filtered residue from alumina production. Field tests were carried out to collect undisturbed samples for laboratory tests and to obtain the following information: Angle of repose of a stockpile (formed with loose residue); Average density of the stockpile (loose residue); Optimal water content for compaction; Compaction degree of the compacted residue (compacted with a tracked excavator).

7 Methodology Residue from alumina production of CBA Companhia Brasileira de Alumínio. Pilot Filter Press dewater the residue until a solid content of about 75%. Quantity of filtered residue used in the tests: approximately 8 tonnes. Equipments used: Munck truck to transport and lift the bags to perform the stockpile test; JCB backhoe to excavate the ditches; Doosan Solar 255LC V excavator to compact the residue. Equipment Excavator Doosan SOLAR255LC-V Track width (m) 0.60 Track length (m) 3.83 Contact area with ground (m²) 4.60 Equipment weight (kg) 24,600 Contact stress with ground (kg/m²) 5,352

8 Methodology Construction of a residue pile (loose material):

9 Results Simulation of a residue pile formation (material considered loose): Approximately three tonnes of residue was used to construct a pile. Dimension: 3.0 m in diameter and 1.05 m in height. The angle of repose measured was 35. The density of the residue in the pile was measured by two different methods: Method Density (g/cm³) Water Content (%) Crimping the beveled cylinder Membrane Average

10 Methodology Laboratory Tests: Standard Proctor compaction tests > two tests were performed: one with the cake structure, and the other without the cake structure. Determination of gravimetric water content.

11 Dry density (g/cm³) Results Laboratory tests: 1,550 1,530 1,510 1,490 1,470 1,450 1,430 1,410 1,390 1,370 1, Water Content (%) Keeping the structures of 'cake' Not keeping the structures of 'cake'

12 Results Laboratory tests: Material Alumina residue dewatered by Filter Press (keeping the original structure the residue has after being filtered here called "cake" structure) Alumina residue dewatered by Filter Press (not keeping the original structures after the filtering process) γd max (g/cm³) wopt (%) Solids Content (%) γd max = maximum dry density; wopt = optimum water content.

13 Methodology Preparation of the area for field compaction tests: Area: 12 m in width and 50 m in length. Inclination: about 2%, to allow drainage in case of rain. On the sides of the area, ditches and windrows were executed to direct drainage. In the centre of the area, two ditches were excavated: 0.75 m in width, 6 m in length and 0.45 m in depth.

14 Methodology 0.45 m 6 m 0.75 m

15 Methodology Simulation of field compaction:

16 Methodology In situ density:

17 Methodology Sample for laboratory tests:

18 Results Field compaction simulation: Number of passes Total γ in situ top (kn/m³) Total γ in situ bottom (kn/m³) Total γ Point 0 (Lab.) (kn/m³) Max Total γ from SP (kn/m³) E top E bottom w in situ top (%) w in situ bottom (%) SC in situ top (%) SC in situ bottom (%) w optimum (%) Δw top Δw bottom CD (%) top CD (%) bottom

19 Results Field compaction simulation: Relationship between field density and number of passes Relationship between compaction degree and number of passes

20 Conclusions Angle of repose of the residue pile formed after dumping the residue from a 2 m height was about 35, which corresponds to a slope with 1V: 1.43H. In the real scale it can be lower. The density of the pile formed this way was approximately 1.49 g/cm³, with a gravimetric water content equal to 31.5%. The compaction in the field using a Doosan Solar255LC V tracked excavator proved to be quite promising in terms of gain in density, and therefore improvement of the disposal site capacity, since the final volume of the residue is reduced. After 12 excavator passes, a 99.5% compaction degree was reached at the top of the layer. However, it is necessary to perform more tests simulating real operating conditions and the effect of rain.

21 Acknowledgements The authors thank: for the resources used to prepare this paper.

22 References Ávila, J.P. (2012) Disposal methods for fine tailings, in Proceedings 19th International Symposium of ICSOBA International Committee for Study of Bauxite, Alumina & Aluminium, October 29 November 2, 2012, Belém, PA, Brazil. Ávila, J.P., Nery, K.D., Freire Neto, J.P. and Pantoja, R. (2012) Dry storage technology Strength and pore pressure development and compactability of tailings, in Proceedings 19th International Symposium of ICSOBA International Committee for Study of Bauxite, Alumina & Aluminium, October 2012, Belém, Brazil. Bánvölgyi, G. and Huan, T.M. (2009) De watering, disposal and utilisation of red mud: State of the art and emerging technologies. Davies, M. (2011) Filtered dry stacked tailings The fundamentals, in Proceedings Tailings and Mine Waste 2011, November 6 9, 2011, Vancouver, BC, Canada.

23 Evaluation of field compaction of a filtered residue from alumina production K.D. Nery UFMG, Brazil; L.F.S. Villar UFMG, Brazil; R.A. Moreno Companhia Brasileira de Aluminio, Brazil; J.P. Freire Neto Pimenta de Ávila Consultoria, Brazil; M. Scarmínio Pimenta de Ávila Consultoria, Brazil; R.S. Junior Companhia Brasileira de Aluminio, Brazil

PRACTICAL COURSE III CLASSIFICATION & COMPACTION. Res. Assist. İREM KALIPCILAR

PRACTICAL COURSE III CLASSIFICATION & COMPACTION Res. Assist. İREM KALIPCILAR Group index REMINDER GI = (F 200-35)[0.2 + 0.005 (LL-40)]+0.01(F 200-15)(PI-10) FOR GROUP A-2-6 and A-2-7 GI = 0.01(F 200-15)(PI-10)