Cement Powder

[still learn'n]

I don't know where to put this but does anybody have any experience with moving cement dust by air thru a hose?

I am looking into building a machine and need to know how much cement dust would move thru a certain diameter hose at 10 psi. Is there a way to figure that out?

Has anybody run a pneumatic semi trailer and hauled the cement powder? Do you know how long it take to unload so much powder?

 

[repowerguy]

Our tanker drivers can blow off a ~ 24 ton load in a hour, less if they really have to.
This is blowing it to the top of a silo mind you. We use a 4” product hose and the trucks have a pro driven roots blower they run at 10-14 psi. If the hose is jumping, you are moving powder.

 

[hosspuller]

I've fought with air/vac systems my entire career. The key to material movement is the specific gravity of the material, amount of feed and air velocity. The bigger the diameter of the hose/pipe the more air (CFM) is required to maintain velocity. It's air velocity not air pressure that moves material.

 

[Theweldor]

I have worked on jobs with portable batch plants. With 4' hose coming of the trailers run into 5' pipe we have been able to unload 24 ton in about 25 - 30 minutes. Just don't stand on the hose because it will throw you right off from jumping around.

 

[Labparamour]

The other thing the pneumatic bulk trailers have is aeration mats at the bottom of the hopper to “fluff” the material as it goes into the hose. It becomes almost fluid-like. Then, some line air into the delivery hose to help keep it moving.
Not sure of the volume of air but, 35 tons through a 4” hose comes off in under an hour (maintaining 15 psi). Also depends on distance and height you’re moving product.

Back in the day, the had turbo conveyors- turbo mounted on the truck stack and the boosted air is what charged the trailer and moved the product.

Darryl

 

[Theweldor]

What helps the process tremendously is a good dust collector. We had a Rex Model S plant that would make 540 yards of concrete an hour and it would do it steadily. I sped up the dust collector a bit to keep up with the air and cement that it was moving and that made so much difference in how fast a trailer could unload. At 540 yards an hour if it took over 20 minutes to unload a trailer you would run out of cement in short order. We would go thru 50 loads a day. It was a real circus to keep all of this going.

 

[still learn'n]

So my plan is to have a venturi at the bottom of a hopper on a special made piece of equipment to make slurry and it says it will pull 26.8 in HG vacuum so in this instance would the hopper still have to be pressurized from the top? I have to figure out how much dust will be coming out of the venturi to be able to know how much my machine will go thru so that why I was wondering. it has a rating for induction of bentonite so how much difference will cement powder be in this instance?

 

[still learn'n]

What kind of dust collectors are recommended?

 

[Theweldor]

You should post a small drawing of what you want to build. You have to aireate the cement in order to keep it moving. It won't work if you try to choke it down at the end of the line. You will loose a your fluidity in the material and the line will plug up. Best to figure out how much cement you need and run a smaller line and keep it moving. You can also down size the blower that way.

 

[still learn'n]

here is my roughly drawn image on what I want to do my plan right now is to use a semi trailer pneumatic tank or hopper whatever you call it for my cement dust hopper.

 

[Labparamour]

Not sure how much you’re batching at a time.
I don’t think I’d push water past your cement silo...I can see powder around the valve setting up over night.
Maybe better would be auger to feed cement into your tank to make slurry then pump it out.

Darryl

 

[Delmer]

A plugged up wet cement line is a whole different ball game than a plugged up pneumatic cement line. I can't see how it would be used that it could take that much water, unless you're talking soil stabilization?

 

[Theweldor]

I have to agree with Labparamour and Delmer. That may work for a bit the first day but not for long and the second day things will be set up to the point it will take hours to clean. If there is any back pressure on the water it is going to take the path of least resistance, which will be into your batcher full of cement. With out some type of mechanical mixing I dought you are ever going to get anything consistent. You could weigh up the cement in a batcher and meter up the water you would need to mix it to the consistency you are looking for and dump both into a mixing tank and then pump it from there Even that takes special pumps and a lot of clean up time when done. That water will wick threw that cement in the scenario that you have there and by morning it will be an ugly mess.

 

[still learn'n]

The cement hopper will be clear empty at end of day and be cleaned up my idea was to use a 570 cubic foot hopper and then fill it out of a pig so there wouldn't be any dust in it overnight it would get refilled up to 16 times a day

 

[Labparamour]

Few places I’ve seen doing grout injection or shotcrete have mixers fed by cement silo with an auger.
It sounds like your 570 hopper is your mixing tank?
Can’t you just pump the slurry from that?

Darryl

 

[still learn'n]

We mix cement powder in to the soil with a reclaimer so I am looking at making a machine to mix the cement dust with water on the go and directly apply it so I will have a water tank on a chassis and then my thought was is to take a single axle pneumatic trailer hopper like a 570 cu ft trailer hopper and put that behind the water tank on the chassis and then either the educator would go on the bottom of the hopper or it would be blown into a hopper with an educator on the bottom of it like this

And then the slurry would either be sprayed onto the top of the soil or we would like to have rippers with tubes on the back to incorporate it into the soil with a shank or ripper kinda like this

But with an eductor system they say it cant have any back pressure so not sure that it would work to inject it unless I put another pump after the eductor to pressurize the slurry and blow it into the injector toolbar.

So this is a diagram of the educator separate from hopper





And this is a diagram what it would be like under the cement hopper
What would work?

 

[still learn'n]

Few places I’ve seen doing grout injection or shotcrete have mixers fed by cement silo with an auger.
It sounds like your 570 hopper is your mixing tank?
Can’t you just pump the slurry from that?

Darryl

I could have a mixing tank sitting onsite and then pump that into an applicator tank wagon with a spreader bar kind of like a liquid manure wagon but that means one more piece of equipment and more time for the slurry to set up. Why I am looking at doing it this way is to get it done the most efficient with as least amount of equipment and of course cheap is always nice to

 

[Labparamour]

Interesting idea.
The methods I’ve seen are direct application of dry cement on ground then large tiller/pavement grinder-type equipment incorporate it into the soil. Another was pumping the powder into a trench then a trackhoe would mix the cement into loose soil and a dozer spread it.
Would the added water of a slurry lessen the ability to stabilize?

Darryl

 

[still learn'n]

Interesting idea.
The methods I’ve seen are direct application of dry cement on ground then large tiller/pavement grinder-type equipment incorporate it into the soil.
Would the added water of a slurry lessen the ability to stabilize?

Darryl

This is what we have been doing but it is harmful to the operators as they have to be out in it to unhook and hook up a water truck to the tiller.

We add water even if it the dust gets spread on top so that don't seem to be a problem. Other people have used a different system and hauled the slurry on site and then spread it but the have to use a product to slow the drying time down

 

[hvy 1ton]

This is what still learn'n is wanting to do minus the premixing and hauling. I started thinking on the same concept after watching this video. I think the biggest struggle is going to be building a control system that can match the flow of water and cement powder to the ground speed for accurate application.