Tag: alumina

Aluminum Smelting: Cooling the Hot Spots!

Published on by John BallLeave a comment

Aluminum smelting is an important process to change alumina ore into aluminum, a lightweight metal.  This process uses high heat for a period of time to separate the oxygen from the alumina.  The temperature can reach over 1000oF (538oC) to cause this separation.  As a reference, two pounds (0.9 Kg) of alumina ore is needed to make one pound (0.45 Kg) of aluminum.  Inside the ovens and exhaust ducts, they are lined with a cement brick to contain the heat and fumes.  Over time, the brick can get weak and have hot spots.  Once the brick is compromised, the system has to be shut down for days to replace the brick.  This is an expensive process and time-consuming.  To help reduce the hot spots and extend the life of the brick, the smelting company was using ¼” copper tubes to blow compressed air to reduce the heat.  This was costing the company a lot of money to operate; so, they contacted EXAIR for a better solution.     

They may be inefficient, but they sure are loud…

EXAIR has been manufacturing intelligent compressed air products since 1983.  And one thing that we know how to do is to save money on compressed air blow-off applications.  For this company above, they had 90 open pipes throughout their plant.  I was able to do a quick calculation for this customer to compare the copper tube to a Super Air Nozzle.  A ¼” copper tube will use roughly 33 SCFM (935 SLPM) of compressed air at 80 PSIG (5.5 bar).  As a replacement nozzle in a hot area, EXAIR recommended a model 1100SS Super Air Nozzle which will use 14 SCFM (396 SLPM) at 80 PSIG (5.5 bar).  With a simple connection, they could mount the ¼” NPT Super Air Nozzle at the end of each tube.  With the cost to make compressed air at $0.25/1,000 ft3, we can calculate the air savings.    

33 SCFM (copper tube) – 14 SCFM (Model 1100) = 19 SCFM savings

The operation for the smelting plant was 24 hours and 7 days a week.  The amount of savings is as follows:

19 ft3/min * 60 min/hr * 24 hr/day * 7 days/week * $0.25/1,000 ft3 = $47.88 savings per week per nozzle.

Since they have 90 nozzles, this would save them $4,309.20 each week! 

How can we do this?  With cooling capacities, it is dependent on the mass of air that can be moved.  With our Super Air Nozzles, we are near an amplification ratio of 25:1.  This means that for every one part of compressed air, we can entrain 25 parts of ambient air.  Also, with our Super Air Nozzles, we can generate a laminar air flow which has a velocity profile that has the air moving in the same direction.  An open pipe has turbulent flow, which means that the velocity is traveling in different directions and not working together.  And the amplification ratio is very low.  I did a demonstration to illustrate this effect here: Video Blog: Laminar and Turbulent Flows.  The large volume of air creates good cooling without using too much compressed air to reduce the hot spot temperatures.  In keeping the temperature under control, they could continue operations and lessen the concern for untimely shut-downs and costly maintenance.

By using air to cool, you can do it safely and efficiently.  As a benefit, the Super Air Nozzles reduced the noise level as well.  Saving a lot of money; having an effective way to reduce stress on the cement bricks; and reducing the noise nuisance were great replacements for this company.  If you would like to speak about cooling applications, you can contact an Application Engineer; even something as large as a smelting oven.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Heavy Duty Line Vac Solves Alumina Spillage Problem

Published on by exaircorpLeave a comment

Spilled alumina material which needs to be vacuumed and returned to the main hopper.

The image above shows spillage of small alumina particles at an aluminum manufacturing plant in South America.  This customer needed a method to vacuum the spilled material and return it to the main hopper.  The ideal solution needed to be compact, simple, and provide repeatable results.  All of these are key aspects of EXAIR Line Vacs, so we began discussing application variables to make a solution recommendation.

Whenever we consider Line Vac applications we always explore the following variables:

  •      Bulk density of the material
  •      Size of the material
  •      Conveyance height
  •      Conveyance distance
  •      Required conveyance rate
  •      Available compressed air supply

The spilled alumina in this application has a bulk density of 1.1 g/cm³ (~68.7 pounds/ft³) which needs to be conveyed to a height of 3.3m (~11ft.).  The conveyance rate is not mandated, but the alumina particles are rather small in diameter and the customer wanted to move as much material as possible in as little time as possible.  Compressed air is readily available at proper pressures and flows, so we were left to determine whether a Line Vac could be a viable solution.  Fortunately we’ve found success in transferring alumina with our Line Vacs in multiple applications before, so we were confident we could find a solution here as well.

The height of this application is 3308mm (~11ft.) – an easy conveyance height for an EXAIR Line Vac.

After exploring the specifics of this application we determined the best solution to be the 2” Heavy Duty Line Vac model 150200.  The 150200 Heavy Duty Line Vac can easily move the alumina to a height of 3.3m at an estimated conveyance rate of 11kg/minute (25 pounds/minute).  There are no moving parts to wear out, which means little to no maintenance and reliable performance each time the Line Vac is used.

Our local distributor assisted with product procurement and in-country technical support.  So even though this customer was in a different continent, we were able to quickly get them the assistance and products they needed to solve their problems.

If you have an application and would like to work with an EXAIR Application Engineer, give us a call and we’ll be happy to help.  1-800-903-9247.

EXAIR Corporation Application Engineers
Techelp@EXAIR.com

Line Vac Brings Additional Solution To Alumina Spill Recovery

Published on by Lee EvansLeave a comment

Mobile spill recovery unit

In my last blog post I wrote about vacuuming alumina dust in an aluminum manufacturing plant in South America.  In that application we were returning spilled alumina to the original hopper so that processing could continue.

This same customer has an additional application to vacuum spilled material, but the new need is to assist mobile spill recovery vehicles (shown above) in vacuuming spills of varying volume. These mobile vehicles are effective for most of the spillage demands they can access, but there are times where additional vacuum is needed, such as when the spill location is beyond the hose length of the system.  In those scenarios additional vacuum hose can be added, but line losses render the performance too low to produce real results.  With this in mind, the end user looked for a point-of-use vacuum boosting solution, and thought about again using an EXAIR Line Vac.

Considering the potential use of a Line Vac, we approached this in the same way as any other pneumatic conveying application, gathering the required information to allow a proper model number selection.  As with the previous application we confirmed the following:

  •      Bulk density of the material
  •      Size of the material
  •      Conveyance height
  •      Conveyance distance
  •      Required conveyance rate
  •      Available compressed air supply

The spills in this facility are comprised of alumina dust with a bulk density of 1.1g/cm³ (68.7 pounds/ft³).  From the floor to the maximum height of the vehicle is a distance of 3.25m (~11ft), and conveying distances were in a range of 3-10 meters (10-30 feet).  The customer had no required conveyance rate, only a requirement to boost vacuuming capacity when needed.

With this information confirmed we were able to make a model number recommendation, the 2″ Heavy Duty Line Vac model 150200.  Adding the 150200 Heavy Duty Line Vac to this mobile spill recovery unit brings additional vacuum flow and conveyance of the alumina through a high velocity airstream, making mobile spill recovery efforts more effective.

If you’re in need of a pneumatic conveying solution, contact an EXAIR Application Engineer (1-800-903-9247).  We’ll be happy to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Another Unique Solution in an Aluminum Processing Plant

Published on by Lee EvansLeave a comment

Fine dust particles needed to be removed from this belt on the underside of a conveyor

A few months back I wrote about the impact of installing Super Air Knives in an aluminum processing plant.  Those Super Air Knives solved a recurring problem with cleaning alumina dust around conveyors and reduced costs for the end user by over $80k.

That same customer has also found a method to remove fine dust from the underside of the conveyor belt in an application area not suitable for an Air Knife.  In this application there was no dust collection system in place to carry away the fines as they are blown off of the belt, so a different type of solution was needed.

Model 150200 Heavy Duty Line Vac provides the vacuum needed to remove the dust fines.

That solution was to install a Heavy Duty Line Vac affixed to a vacuum hood to remove fines from the belt and convey them back to the head chute.  The only problem with this setup was that the 2” Heavy Duty Line Vac produced a bit too much vacuum flow than what was really needed in the application.  So, a pressure regulator was installed to allow for adjustment and fine tuning of the vacuum solution.  The customer was able to adjust the operating conditions for the Line Vac and minimize compressed air use while maximizing the vacuuming effect on the fines stuck to the conveyor.

The Line Vac used in this application quickly and easily solved a chronic problem plaguing this manufacturer.  By installing this vacuum solution they were able to prevent build-up of dust and debris underneath the conveyor which originally required shutting down the line to clean.  This improved process uptime, reduced cleaning costs, and increased throughput in the application.

If you have an application in need of a vacuum solution, consider an EXAIR Line Vac.  And, if you have any questions, contact an EXAIR Application Engineer.  We’ll be happy to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE