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MINE 432 Introduction to Process Control

MINE 432 Introduction to Process Control. John A. Meech Professor and Director of CERM3 Centre for Environmental Research in Minerals, Metals, and Materials. To Be Ore, or Not to Be?. An ore is a mixture of minerals, one or more of which has value, that can be mined: At some time

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MINE 432 Introduction to Process Control

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  1. MINE 432Introduction toProcess Control John A. Meech Professor and Director of CERM3 Centre for Environmental Research in Minerals, Metals, and Materials

  2. To Be Ore, or Not to Be? • An ore is a mixture of minerals, one or more of which has value, that can be mined: • At some time • At some place • For a profit • What is not ore today, may become ore in the future • What is ore in one place, may not be in another

  3. Mineral Processing Stages • Liberation (comminution or breaking of rock) • Blasting • Crushing • Grinding • Separation (valuable minerals from waste) • Gravity • Magnetic • Electrostatic • Flotation • Extraction of values from mineral concentrate

  4. Operating Plant Targets • Maximize Product Quantity (Production) • Tonnage rate of ore (say 100,000 tpd) • %Recovery of Valuable Component (say 92%) • Maximize Product Quality (customer needs) • Concentrate grade (say 28 %Cu or 54 %Zn) • Impurity component levels (Bi, Sb, Pb in ppm) • %H2O (both minimum and maximum) • Particle size constraints (top size and ultra-fines)

  5. Grade vs. Recovery • Often, there is a quality/quantity trade-off • One goes up, the other goes down

  6. Grade vs. Recovery • Often, there is a quality/quantity trade-off • One goes up, the other goes down

  7. Process & Instrumentation Diagrams • Process diagrams depict a network of stages or events through which materials flow • Process flowsheets represent unit operations through which solids, liquids, or gasses flow and are transformed • Control system diagrams (or programs) represent stages in a system through which signals, information, or data flow

  8. What is a Process? A Process takes inputs and combines them in a way to produce one or more outputs In process control, only a single input is involved in each block Process Output Input

  9. ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ What is a Process? Process Continuous Batch Discrete Event Discrete State Start Up Non- stop Shut Down after: John Sowa, 2001. Processes and Causality, <www.jfsowa.com/ontology/causal.htm>

  10. Batch or Discrete Process Person Waiting Person gets on bus Person on bus Bus Arriving Bus stops (an Event) Bus waiting Bus starts (an Event) Bus leaving Execution of a Bus Stop Petri Net model (cumulative) - works well with discrete agents/products represented as tokens (an Event) after John Sowa, 2001. http://www.jfsowa.com/ontology/causal.htm

  11. Batch or Discrete Process - Loading Shovel Waiting Shovel begins to Load Shovel Waiting Truck Driving to Spot Truck stops (an Event) Truck being Loaded Truck starts (an Event) Truck Driving from Spot (a State) (a State) (a State) (an Event) (a State) (a State) after: John Sowa, 2001. Processes and Causality, www.jfsowa.com/ontology/causal.htm

  12. Batch Processes in Mining Drilling Loading Explosives Blasting Digging Loading Ore/Waste Hauling Ore/Waste Dumping Ore/Waste Maintenance Returning Empty

  13. What is a Control System? • A control system tries to keep an important process output variable as close to a target level (or set point) for as much of the time as possible • The system responds rapidly and stably to compensate for changes in other variable that affect the output or to desired changes in the target level of the output set point

  14. Why Control? • Increased Production Capacity • Increased Product Quality • Decreased Energy (Utility) Usage • Decreased Raw Material Usage • Reduction in Capital Investment • Savings in Equipment Maintenance and Replacement • Improved Safety and Improved Working Conditions • More Consistent and Predictable Plant Performance • Reduction in Labour Costs - by attrition and skills upgrading - where turn-over rates are high

  15. Elements of a Control System Load Block System Load Variable Controller Final Control Element Process Error System Set Point + – Control Signal Control Variable System Output Measuring Device Measured Variable

  16. 1.0 1.0 Proportional t=0 t=0 Integral Derivative Elements of a PID Control System Regulator Control One or the Other Load Block System Load Variable Servo Control ? Final Control Element Process Error System Set Point + – Control Signal Control Variable System Output Measuring Device Measured Variable

  17. Response to a Set Point Step Change

  18. Response to a Set Point Step Change

  19. Response to a Set Point Step Change

  20. Response to a Set Point Step Change

  21. Response to a Set Point Step Change

  22. Response to a Set Point Step Change

  23. Response to a Load Step Change

  24. Response to a Load Step Change

  25. Response to a Load Step Change

  26. Response to a Load Step Change

  27. Response to a Load Step Change

  28. Response to a Load Step Change

  29. Unit Operation – grinding • Ball-mill • rotating drum with steel balls cascading onto the rocks to break them into finer particles Grate-Discharge Typical Installation showing Covered Trunnion and associated Electric Motor

  30. Unit Operation – size separation • Hydrocyclone – separation by size

  31. Unit Operation – slurry pump Variable Frequency Drive Slurry Pump

  32. Unit Operation – conveyor belt Conveyor belt feeding a stacker/reclaimer

  33. From crushers Crushed Ore Bin Building a Flowsheet - 1

  34. From crushers Crushed Ore Bin Feed Conveyor Building a Flowsheet - 2

  35. From crushers Crushed Ore Bin Ball Mill Feed Conveyor Building a Flowsheet - 3

  36. From crushers from Mill Water Supply Crushed Ore Bin Ball Mill Feed Conveyor Building a Flowsheet - 4

  37. From crushers from Mill Water Supply Crushed Ore Bin from Mill Water Supply pulp H2O Ball Mill SUMP Feed Conveyor Pump Building a Flowsheet - 5

  38. From crushers from Mill Water Supply Crushed Ore Bin from Mill Water Supply pulp H2O Ball Mill SUMP Feed Conveyor Pump Building a Flowsheet - 6

  39. From crushers from Mill Water Supply Crushed Ore Bin from Mill Water Supply pulp H2O Ball Mill SUMP Feed Conveyor Pump Building a Flowsheet - 7 Hydro cyclone

  40. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply pulp H2O Ball Mill SUMP Feed Conveyor Pump Building a Flowsheet - 8

  41. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply pulp H2O Ball Mill SUMP Electric Motor Feed Conveyor Pump Adding Actuators andFinal Control Elements - 1

  42. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply VS Drive Motor pulp H2O Ball Mill SUMP Electric Motor Feed Conveyor Pump Adding Actuators andFinal Control Elements - 2 VS = Variable Speed

  43. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply VS Drive Motor pulp H2O CS Drive Motor Ball Mill SUMP CS Drive Motor Electric Motor Feed Conveyor Pump Adding Actuators andFinal Control Elements - 3 VS = Variable Speed CS = Constant Speed (to be ignored for this exercise)

  44. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply VS Drive Motor pulp H2O Ball Mill SUMP H2O valve Electric Motor Feed Conveyor Pump Adding Actuators andFinal Control Elements - 4 VS = Variable Speed

  45. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply H2O valve VS Drive Motor pulp H2O Ball Mill SUMP H2O valve Electric Motor Feed Conveyor Pump Adding Actuators andFinal Control Elements - 5 VS = Variable Speed

  46. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply H2O valve VS Drive Motor Weigh Scale pulp H2O Ball Mill SUMP H2O valve Electric Motor Feed Conveyor Pump Adding Instrumentation - 1 VS = Variable Speed

  47. From crushers To Flotation Separation Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply H2O valve VS Drive Motor Weigh Scale pulp H2O Ball Mill SUMP Sump Level H2O valve Electric Motor DP Cell Feed Conveyor Pump Adding Instrumentation - 2 VS = Variable Speed DP = Direct Pressure

  48. From crushers To Flotation Separation Pulp Density Meter Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply H2O valve VS Drive Motor Weigh Scale pulp H2O Ball Mill SUMP Sump Level H2O valve Electric Motor DP Cell Feed Conveyor Pump Adding Instrumentation - 3 VS = Variable Speed DP = Direct Pressure

  49. Particle Size Monitor From crushers Pulp Density Meter Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply H2O valve VS Drive Motor Weigh Scale pulp H2O Ball Mill SUMP Sump Level H2O valve Electric Motor DP Cell Feed Conveyor Pump Adding Instrumentation - 4 To Flotation Separation VS = Variable Speed DP = Direct Pressure

  50. Particle Size Monitor From crushers Hydro cyclone from Mill Water Supply Crushed Ore Bin from Mill Water Supply VS Drive Motor Weigh Scale pulp H2O Ball Mill SUMP Sump Level H2O valve Electric Motor DP Cell Feed Conveyor Pump Adding Control - 1 To Flotation Separation Pulp Density Set Point + – Pulp Density Meter Pulp Density Controller H2O valve VS = Variable Speed DP = Direct Pressure

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