Re: Drying Millscale
You should consider using of fluidizing bed dryer. This should include hot air fluidizing, with/without mechanical shaking. ■
Re: Drying Millscale
Originally posted by nwood
Hello,
I’m working on a new project that takes mill scale (iron oxide waste from the steel industry) and uses it in products for increased density. The mill scale will need to be dried to 3-5% by weight and we will use approximately 4000lb/hr. The mill scale enters our plant at a 15% moisture by weight. Mill scale arrives to use in various sizes but most is in the .020-.030” range but occasionally there are chunks as large as 1” in diameter. The mill scale has a bulk density of about 120lbs/ft^3. I'm wondering what type of system will work the best and be the most effiecent? Lower intial capital cost will also be a big consideration.
Thanks for the help,
Nate Wood
Do it on the cheap:
Do it exactly the opposite way potatos and sugar beets are cooled:
Potatos and sugar beets are piled around long lengths of perforated culverts where cool air is blown into the culverts and circulated through the potato or beet piles-just make sure to plug the opposite end of the culvet pipe other wise the desired heating effect will be lost. ■
Re: Drying Millscale
Hey Guys,
Thanks for the reply. Below are just a couple more quick thoughts and questions.
1. Mill Scale has a bulk density of 120lbs/ft^3 when piled. We have found it very hard to get any air movement through the material when it is piled because of the density. We have had good results when we can just spread it out thin on the floor and let it air dry.
2. Is there a reputable company that you know of the deals with vibrating fluidized beds? Again we would need to do about 1lb/sec with this system.
3. Right now we are looking at a rotary dryer. Seems costly and slightly overkill for what we want to do so other machinery and ideas like drying in a pile are welcome.
Thanks,
Nate ■
Re: Drying Millscale
Have you ever seen a paddle dryer in operation? Would it work with this abrasive material? ■
Drying Millscale
Paddle Dryers are very well suited for your application.
The advantage of the paddle or shovel dryer is the heat transfer by contact with the heated drum. The more efficient you mix your product inside the paddle/shovel dryer the better. You are not depending on any air movement.
Our Paddle/shovel mixers are for example used in mixing iron ore, quartz, steel works, coal dust and other high abrasive products.
We, AVA-Huep GmbH, are specialists in mixing and drying technologies. We are especially ably to design robust mixers and dryers for heavy duty applications.
Visit us at: www.ava-huep.com
After a first calculation of your process we will be able to offer to you our technology. Please submit us your contact details either to g.gutmann@ava-huep.de or to t.peterson@ava-americas.com ■
Re: Drying Millscale
Your post caught my attention. VENTILEX is a fluid bed drying/cooling manufacturer and we are currently running testing on Millscale.
Please contact us and ask for Gary. Mention this post. We'd be happy to discuss your needs and see where we can help. Our dryers are the most energy efficient made.
VENTILEX USA Inc.
866.265.6823
www.aggregatedryer.com
Regards,
Bill ■
Re: Drying Millscale
What are you intending to use as your heat source?
If you have steam or hot oil available, the capital cost of an indirect dryer may be better. If you need to burn oil or gas to generate the heat, you may find it better to go for a direct heated dryer and allow the combustion gas to do your drying directly. I would guess with your process contamination of the product with combustion producs won't be a problem>
If you do look at a direct heated system, don't forget to look at the total system cost, the dryer iself on such a system may be cheaper but there may well be additional / larger equipment required for the total system, such as burners, fans, filters, scrubbers, etc. that increases the total cost. ■
Dryer
Dear Mr. Wood,
You may want to consider HOLO-FLO units. These are essentially hollow screw flight design having an indirect convectional heat exchange between the product and the heat transfer medium. These are easy to operate and very reliable. It is used in the steel industry due to high abrasion conditions. If you are interested, please send the following info to us so we can provide you with sizing and pricing estimates.
Feed rate: lb/hr
Initial moisture content:
Desired moisture content:
Product inlet temp. : F
Product outlet temp: F
Oil temp: F
Specific heat of product: btu/lb f
Bulk density: lb/cuft
Please send to jiggger2003@yahoo.com
Thank you. ■
Filtering Dried Mill Scale
We are currently using a 6,000 CFM Great Lakes 'RoboVent' Dust Collector to collect mill scale fines from the exhaust of a Carrier Vibrating bed dryer. The mill scale is slightly oily and heated to 225 degrees F. The filters in the dust collector are Polyester HO, 140 pleats, 2 Polyband Outer / Inner Core filters. We are generating several hundred lbs an hour of fines.
The fines are bridging the pleats and effectively rendering the filters useless after less than 24 hours of running. We are wondering whether it is the oil is volatilizing or the amount of dust being generated which is plugging the filters.
Would a cyclone collector inline between the dryer and the dust collector help reduce the load on the filters? Is this a common practice, or is there a better way to do this? ■
Re: Drying Millscale
Bob K
Looking at your location, and guessing that the collector is outside & uninsulated, you may have created a large dehumidifier. As the hot gas cools through the collector, water vapour & possibly oil mist is condensing out and collecting on the bags thus trapping the fines in the cartridge pleats.
I have seen this happen in lots of collectors where the owner doesn't want the collector to take up room inside, but doesn't want to pay to keep it warm outside either.
Hundreds of lbs/hr doesn't strike me as excessive for a collector of that size & material of that density. A cyclone or drop out box would reduce loading on the filters if that is in fact the problem. ■
Equpment For Drying Millscale
Hi Nate,
A very effective piece of equipment for this application is a METSO MINERALS HOLO-FLITE. This is a sturdy, reliable thermal processor which can be used on steam or hot oil to dry a variety of powdered and granular material to a controlled dryness.
Should you be interested to pursue it further, please send me an email and we can go into more detail.
Rental equipment is available to get you off the ground and running relatively cheaply while you are waiting for your production equipment to be delivered.
Regards and Happy Holidays
Ken B. ■
Drying Millscale
Hello,
I’m working on a new project that takes mill scale (iron oxide waste from the steel industry) and uses it in products for increased density. The mill scale will need to be dried to 3-5% by weight and we will use approximately 4000lb/hr. The mill scale enters our plant at a 15% moisture by weight. Mill scale arrives to use in various sizes but most is in the .020-.030” range but occasionally there are chunks as large as 1” in diameter. The mill scale has a bulk density of about 120lbs/ft^3. I'm wondering what type of system will work the best and be the most effiecent? Lower intial capital cost will also be a big consideration.
Thanks for the help,
Nate Wood ■