Selecting a

STEEL GRIT RECYCLING SYSTEM

As you look at the various Grit Recycling Systems on the market today, you can see that they use different principals of operation to accomplish the same goal.

Blast, vacuum and classify steel grit.

All day long the “System” must repeat the operations of:

1. Blasting (send a mixture out a pressure vessel and hose to a nozzle)

2. Vacuuming (pull the grit back to be recycled)

3. Classifying (cleaning and classification of steel grit ready for blasting)

While the three operations must happen 1,2,3 and repeat 1,2,3, etc., each operation is a separate function.

In fact, that is how we design a “System”. By taking each individual process and selecting the BEST method for each process.

“ We define “Best” as the method that meets the level of performance that is required by the users (minimum + contingency)”

BLAST:

1. Single chamber: 1, 2, 3, or 4 pots

· Pot must be depressurized to refill

2. Double chamber: 1, 2, 3 or 4 pots

· Pot can depressurize and refill without stopping (true continuous)

· The lowest number of cycles per day is preferable

· Number of pots is determined by the space available and quantity of grit required.

· Larger pots require less refilling per day (lower number of “cycles”)

VACUUM:

1. Single hose: 4”, 5”, 6”, 8”

2. Double hose: 4”, 5”

· Most users want to vacuum up grit in 1/2 the time it takes to blast

· The size and number of hoses determines the amount of air flow required.

· Small hoses are easier to handle (4-5” hoses are easiest)

· Big hoses move the most tonnage but are hard to handle reducing “actual” tonnage.

CLASSIFY:

1. Airwash UNDER VACUUM

· Vacuum air “moves” grit AND “cleans” it.

· Dual use reduces vacuum friction loss, reducing vacuum “power”

· Limited ability to separate “fines” because airflow fluctuates as operator (human) vacuums grit

2. Airwash UNDER NO VACUUM (atmospheric pressure)

· Most common method in the world

· Adjustable to allow selection of the SIZE of grit that is kept

· Will separate as fine as 80-90 mesh

· Requires small fan-filter with CONSTANT airflow

3. Magnetic drum

· Only separates magnetic from non-magnetic

· Works best on larger particles

· Will not remove dust “fines”

· Reduces “load” on airwash

Because each operation is separate, they must all be “connected” using some method. Here are the options:

CONNECTIONS:

1. Pneumatic transfer using vacuum airflow

· Simple in concept but reduces the power of the vacuum

· Airflow at end of line carries “fines” out of the system

· Hard to control, turning on-off

2. Bucket elevators and augers

· Most common method in the world (used in all types of blast machines, rooms)

· Can fit in very tight spaces

· No loss of vacuum power

· Must be designed to handle grit (heavier duty)

3. Conveyor belt

· Bounces grit causing loss

· Must be covered to meet OSHA requirements

· Cannot exceed 30-40 degree angle

GRIT STORAGE:

· Most users want enough storage to handle what they could blast our in one day. Less than that and you will have to vacuum before you can continue blasting.

TRAILER:

· Most users want a trailer that can handle the weight of the grit and equipment.

· If you can get permits for overweight loads, make sure the trailer can handle the total load.

Now you know some of the options available. You must determine YOUR REQUIREMENTS. What do you want the system to do? See the information on Sample Specifications.

0SYSTEM.DOC