antti jaatinen 1

7/29/2019 Antti Jaatinen 1

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Feed control of a mobile rockcrushing plant

Pasi Airikka

Metso Automation

Finland

Presented by Antti Jaatinen



© Metso

Metso facts & figures

2

Feed control of a mobile rock crushing plant

• Metso is a global supplier of technology and services to various industries

• Metso has three business segments with >30 000 employees in more than

50 countries

1. Mining and Construction

2. Pulp, Paper and Power

3. Automation



© Metso

Feed control of a mobile rock crushing plantContent

• Mobile rock crushing plant

• Lacking plant-wide controls

• Achievable benefits

• Feed control philosophy

• Simulation case

• Conclusion

3



© Metso

Mobile rock crushing plant

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• Crushing is about processing blasted rocks(feed material) into aggregates of different

smaller sizes (fractions) based on crushing

and screening

• Crushing takes place in consecutive crushing

stages (primary, secondary...)• Mobile crushing and screening units have

tracks (Metso Lokotrack) allowing moving for

better positioning on-site

• Typical operable (on/off or analog) actuators:

conveyors, feeders, crushers

• Changing crushing plant layouts are reality!



© Metso






• Simulation case

• Conclusion

5



© Metso

Lacking plant-wide controls

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• Often (basically always) the only crushing plant controls are atmachine-automation level having no connection to other crushing units

• Crushing units are not well-instrumented to indicate material flows (e.g

belt scales needed)

• Human-operating feeding (dumper or excavator) poses the first source

of non-constant process flow (disturbance!)• Feed size distribution (and moisture) is another source of disturbances

• Conveyor speeds and crusher parameters act as disturbances as well

• Plant layout on-site is subject to changing at any time

• Mobility of crushing units prevents cabling and linking them together

• Yet, above facts should not be an obstacle for designing and

implementing plant-wide controls for stabilizing and regulating feed

flows which rely on additional level sensors



© Metso






• Simulation case

• Conclusion

7



© Metso

Achievable benefits

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• Well-designed rock material feed flow controls come with variousbenefits:

- Regulation and stabilization of production

- Compensation of process disturbances such as feed size distribution

changes and crusher wear

- Reduced manual intervention

- Reduced downtime that might be due to overflowing feeders, feed chutes,

screens or crushers

- Automatic start-up and shut-down sequences

- Centralized control room (in an excavator!)

- Improved safety due to centralized plant operation

- All the used plant laytous (1+2, 1+2+3 etc.) can be considered



© Metso






• Simulation case

• Conclusion

9



© Metso

Feed control philosophy

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• There are four different plant configuration (layout) combinationsavailable for a 3-stage mobile crushing plant

• Feed controls to be designed and implemented separately for eachplant layout in particular

• Next, a design example for 1+2+3 plant is given (all the others are

described in the full paper)

Different plant combinations. Plant layout overview for 1+2+3.



© Metso


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• For 1+2+3 mobile crushing plant, there are three analog actuatorsavailable (primary crusher feeder, secondary crusher feeder and

secondary crusher inclining conveyor) and six measurements (3 x

crusher cavity level, secondary feed chute level, 2 x conveyors)

• Regulated variables are secondary crusher feed chute level and

tertiary crusher cavity level

Controlled variables (CV), manipulated variables (MV) and disturbance variables (DV) for

1+2+3 mobile crushing plant.



© Metso


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Control diagram for rock crushing plant layout 1+2+3 with two main control loops and

several limiting control loops.

DB = deadband

mPPI = modified Predictive PI controller

MIN = minimum selector



© Metso

Simulation case

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• Feed control simulation case for a mobile crushing plant layout 1+2(Metso Lokotrack, LT units) with control variables (CV) of secondary

feed chute level and secondary crusher cavity level

• Manipulated variables (MV) are primary feeder (0-100%) and

secondary feeder (0-100%) and conveyor (0-100%)

Control diagram for rock crushing plant layout 1+2.



© Metso

Simulated responses

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• Secondary crusher feed chute and cavity level are regulated at targetvalues against following changes: at t = 0 (start-up), t = 20 min (10%

change in recycling material, t = 40 min (CSS change)

Simulated

responses

based on the

designed feed

control strategy

for plant layout

1+2.



© Metso

Conclusion

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• It was shown how plant-wide feed controls can be designed for differentmobile crushing plant layouts (4 combinations in total)

• Plant-wide controls link crushing units into one entity allowing co-ordinated

and well-functioning regulation of rock materia flows (levels)

• Control philosophies rely on modified predictive PI controllers (mPPI,

Airikka 2011), limiting controllers, settable deadbands for regulationvariables, measurement filtering and feed-forward controls

• Feed control allows compensation of feed size distribution and moisture,

crusher parameter changes (e.g CCS), change of screen nets, conveyor

speeds, in-coming feed material flow changes

• A simulated example with resulting responses was shown

• Future work will be focusing on implementing these control strategies

(actually, on-going in Finland on a mobile crushing plant)



Pasi Airikka

Metso Corp. , Finland

[email protected]

www.metso.com

mailto:[email protected]

http://www.metso.com/

http://www.metso.com/

mailto:[email protected]

antti jaatinen 1

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