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Dust Suppression Modelling


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This is my first time using this forum so I hope I am posting this in the correct section.


I am currently busy with a problem involving the dust suppression program at an open pit mine. In open pit mines water trucks are used to maintain the condition of haul roads and reduce mine dust. Water trucks load water from refilling stations and traverse the road to spray water. After the water is exhausted, the water truck travels toward one of water stations for refilling and then continues to traverse the roads to satisfy the watering patterns. The water trucks run 24 hours per day.In practice the watering frequency of each road is related to the traffic intensity of haul trucks. The period of effectiveness, after the road has been watered, can range from 30 minutes to 3 hours. Regular light watering at approximately 0.3-0.5l/m2 is much more effective than infrequent heavy watering.


To simplify the problem each road will be assigned a watering frequency (e.g. every 60 minutes) and a sliding time window (e.g. 10 minutes). The water can therefore be sprayed on the road within the given time window (e.g. 50 to 70 minutes). If the trucks service the road more frequently than every 50 minutes the road will be over watered and this can cause a host of problems. If the trucks water the road less frequently than every 70 minutes dust aggregation will start becoming problematic. In order to satisfy the water demand of the roads, it is possible that a truck waters a road segment first, then travels along the next road segment without watering it, and then waters another road segment. The road segment that a water truck traverses without watering is called a dead heading. A bidirectional road has to be watered in each of the two directions


Empty water trucks are refilled at the refilling stations. A refilling station can serve a limited number of trucks at the same time. Also, a limited number of trucks can wait before being refilled. Hence, every refilling station has two kinds of capacities: the capacity for refilling the trucks and the capacity for holding trucks. If a refilling station is overloaded, some trucks need to be reassigned to a different refilling station.


My main problem at this stage is how to model the dust aggregation on the haul roads. I started by setting up each road as a source server sink and then only displaying the server queue. The entities can then be modeled as dust clouds. The trucks then tend to the servers as operators. This still does not give the desired outcomes. I’m struggling to schedule the trucks to move on the shortest route and then return to the nearest filling station once they have depleted their water supply. Does anyone have any other ideas on how to approach the problem?


Thanks for your help!


Regards

Carl-Gustaf Gericke

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I would probably sub-class Path to create your own custom path object - maybe call it DustyRoad.


Then on DustyRoad you might add a Level State called DustLevel. Then it sounds like DustLevel would start at 0.0 and increase at a given rate. That DustLevel Rate could be a simple time function or a function of ambient temperature, average traffic level or anything else.


You could also implement step changes to the current DustLevel Value each time a hauling truck travels it. And then I guess you would set the Value to 0 each time it is sprayed. At a simple level, each water truck or dispatcher could just look at the current DustLevel Value at any DustyRoad of interest.


But you could make DustyRoad as smart as you wanted, perhaps having it call for spraying when it reaches a certain DustLevel Value (using a Monitor). You could have each DustyRoad record it's own average dust emission level in whatever form is appropriate and even roll it up to the Mine or model level for a measure of the overall effectiveness of your dust suppression strategy.


For each feature you add to DustyRoad you would expose a property allowing users to customize the behavior. For example, you might have a property for the name of the state into which you roll up the dust emission statistic.


This is an interesting problem. I'd love to hear/see how you make out with this.

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Check out the "Pick Up Drop Off Flow" simbit...


Tanks associated with the vehicles will solve the water usage problem....


Subclassing a path and adding a tank to it will solve your aggregation problem as you can use a flow equation to simulate the accumulation....


You can then simply scale the path tank down with the discharge or flow rate of the water trucks tank...


Hope this helps...

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Hi all,


I need help and guidance. I started with this dust suppression model and the file that I attached is what I came up with. I am going to make the dusty paths a sub-model but first I want to figure out all of the logic on a smaller scale. Now currently I have three paths that get watered. The water capacity/need of the path is represented by the three tanks and sinks next to them. Tank 1 is the filling station and it can be assumed that there will always be water. So the three paths represented three different levels of traffic. A higher traffic path has a faster flow rate towards the sink therefore it will need more frequent watering. What I need now is to define lets say 14 water trucks that I can separately monitor, that wont get destroyed at the end of their run and that park at a parking station until they are needed again. I also want to attach a certain failure logic to each of the trucks. I have tried using vehicles but I'm struggling to get the process logic working. I'm am still quite new to simio so I might be missing things. I'll appreciate any inputs.


Thank you very mutch

Carl-Gustaf

Dust.spfx

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