On-line instrument for measuring Parameters in Industrial Thickeners. Concha F., Sbárbaro D.. Pereira, A., Segovia J.P., Vergara A.

Transcription

1 On-line instrument for measuring Parameters in Industrial Thickeners Concha F., Sbárbaro D.. Pereira, A., Segovia J.P., Vergara A. 1

2 Content Introduction Thickening mathematical model New on-line Instrumentation Measurements in a copper concentrator Advanced control strategies Conclusions Acknowledgment 2

3 Introduction Physical process in a thickener. Typical instruments used in thickeners. Metallurgical an classical automatic control.

4 Hindered Settling and Consolidation Hidered settling Consolidation 4

5 Mathematical Model Properties of the solid an fluid involved in thickening. Dynamical thickening process model. ' fbk ( ) e( ) q( t) fbk ( ), for 0 1 t z g z f q k ; 0 5

6 Solid flux-density function f bk ( ) Solid effective stress e( ) Constitutive equations Two equations describe Hindered settling and Consolidation 0.0E E E E+04 e ( )=5.0exp(14 ) -1.0E E E E-05 f bk ( )=-6x10-4 * *(1- ) E E Solid volume fraction 0.0E Solid volume fraction fbk ( ) u (1 ) c ( ) e 0 for c exp( ) for c 6

7 Laboratory Instrument to determine the settling velocity 7

8 Solid effective stress e, Pa Laboratory Instrument to determine the compressibility of the sediment Experimental data Determined parameters Solid volume fraction 8

9 SediRack on-line general view 9

10 Sedirack On-line components 10

11 Sedirack On-line settling tubes and settling velocities 11

12 Settling velocity measurement 12

13 Sedirack On-line Floc window 13

14 ColumnTest Columntest H L Inlet pump Pressure PT 02 Underflow Pump z() ' fbk ()() e gf F Dbk f d 1 () D 14

15 Components of the ColumnTest Air flow controller to maintain constant flow in the instrument. Spool. Level sensor detector. Descent sensor detention. Differential pressure measurement. Washing cable and sensor. Data processing. 15

16 Results of Measurements in a Copper Concentrator 16

17 SediRack-on line 17

18 Settling velocities and solid flux density function Initial settling velocities vs Solid flux density function v s 18

19 Settling velocities and flux density function Same flocculant at two dosage. Two different floculants at same dosage. 19

20 Feedwell dilution Dilution in the feedwell Thickener feed Thickener feedwell 20

21 Floc size and size distribution measurements Floc window Normal and digitalized images of flocculated copper tailings 21

22 ColumnTest 22

23 altura [cm] Supernatant and sediment height measurement The supernatant and sediment bed height can be measured whith the columntest. Usualy these two variables need two different instruments Nivel de Sedimento y Agua Clara en Espesador de Molibdeno P4 (7 Marzo de 2012) Nivel de Sedimento Nivel de Agua clara tiempo [días] 23

24 Altura [m] Concentration profiles The figure shows the concentration profile in time for a copper tailing thickener Concentración [pu] N Perfil

25 altura [cm] Concentration profiles Left: The figure shows the concentration profile for a molybdenite thickener. Right: Profile in time. 240 Mediciones Columntest Espesador R5(16 de Enero 2012) Lts. sol/ Lts. solucion 0.04 Lts. sol/ Lts. solucion 0.07 Lts. sol/ Lts. solucion 0.1 Lts. sol/ Lts. solucion 0.13 Lts. sol/ Lts. solucion 0.16 Lts. sol/ Lts. solucion 0.19 Lts. sol/ Lts. solucion 0.22 Lts. sol/ Lts. solucion 0.25 Lts. sol/ Lts. solucion 0.28 Lts. sol/ Lts. solucion tiempo [días] 25

26 Solid inventory in a thickener Once the solid effective stress ( e ) and the concentration profiles z( ) in a thickener are known, the total mass M I of solid contained in the thickener can be calculated. z c M I ss L zc L () z dz 0 26

27 Thickening Control strategy SEDIRACKONLINE COLUMTEST Identificacio n de parametros de Fbk Dosificacion Optima de Floculante medio DP f k j ) g h ( ) ( s f s f Escalamiento del Feedwell N(ŷ) Estimación de la Masa o Stock CAMAR A Modulo Procesamiento de Imagenes Feed Pulp FT 01 DT 01 Density and Flow LT 01 Flocculant Pump Transmisores Presión Diferencial con Sello Remoto H L H L H L H L Sediment Level LT 01 Turbidity Transmitters AT 01 FFC 01 Flow Fraction Controller M SV 01 Frecuency Speed Drive Inlet pump Pressure PT 02 Sellos Remoto Underflow Pump Sediment Column Pressure Frecuency Speed Drive PT 01 SV 02 Overflow SetPoint Fi DT 02 Fi(ρ) FT 02 Underflow Density and Flow Fuzzy PI Fuzzy PI 27

28 Conclusions Two new on-line instruments were developed to determine the material parameters of the incoming pulp. The instruments were successfully validated in a Chilean copper concentrator. The SediRack and ColumnTest can also be used to audit a thickener by determining the operational variable such as feed dilution, optimal flocculant selection and dosage, floc size distribution and solid inventory. 28

29 Conclusions For process control purpose the sedimentationconsolidation model needs on-line information that can be obtained by the new on-line instruments. The knowledge of the phenomenological model an the two thickening parameters, permit the development of advanced control strategies. 29

30 Acknowledgments We acknowledge financial support from AMIRA project P996, Innova Corfo project 08-CM01-17 and Conicyt/Fondap Project

31 THANK YOU FOR YOUR ATENTION 31