How to make a Typical Laundry Detergent using an O’Brien Agglomerator
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This shows a step-by-step procedure to make a common US consumer type laundry detergent using an O’Brien Agglomerator. This is a good basic detergent that cleans well, good in appearance, saves equipment cost, raw materials cost and labor.
This example will use a typical US medium-quality consumer type laundry detergent formula. It uses commonly available ingredients.
This formula uses only the major detergent components. Ingredients present in minor amounts are excluded as they have no effect on processing. These include florescent brightening agents, antiredeposition agents, a wide variety of polymers, perfume, colorant, and some others. Other common ingredients, such as oxygen bleach sources, are not addressed here to keep this simple. A good reference to further refine any single detergent is “Handbook of Detergents: Formulation”; By Michael S. Showell.
The total batch is 50 lb, about one cubic foot.
The formula is: Soda Ash 30.00 % 15 lb inexpensive grade such as powdered soda ash
STP (sodium tripolyphosphate) 10.00 % 5 lb inexpensive grade - powdered STP
Salt (sodium chloride as a filler) 35.00 % 17.5 lb other fillers possible (i.e. sodium sulfate)
Water (neutralize sulfonic acid to LAS) 2.00 % 1 lb excess water – will be dried off later
Anionic Active (sulfonic acid) 5.00 % 2.5 lb will neutralize to LAS
Nonionic Active 10.00 % 5 lb
Sodium Silicate (N grade PQ) 10.00 % 5 lb
Dry off excess water if necessary -2.00% lost in processing
100.00 % 50 lb batch
The O’Brien Benchtop Agglomerator is the only equipment needed to make this detergent batch. Screening to remove undersize and oversize is often used to make a consumer desirable final product..
Be sure the agglomerator is ready. The discharge slots are covered and the drum empty.
Place the soda ash and salt filler into the agglomerator.
Rotate the agglomerator counter-clockwise (CCW) at a slow speed for about one minute to mix the powders.
There are four liquids to add: water, sulfonic acid (produces the anionic active LAS), nonionic active and liquid silicate binder. Separate spray vessels and pipes are convenient for each liquid to reduce the mess and speeds up batching time. A single spray system can be used, but it MUST be clean and dry for each liquid. Note how the system below handles this issue.
Note, the lower right hand corner in the above picture. This shows a spray vessel used for liquids, They can be pumped (the white plastic pump on the LHS) or a pressure cap to seal the vessel for air pressure to spray.
Increase the rotation speed to get a Falling Curtain as in the drawing below.
If the powder is very fine (often happens when a large amount of the powder base is minus 100 US Mesh or smaller), an additional consideration is required. WHen spraying the first liquid, turn the spray nozzle so the spray is at the “5 o’clock” position. Later, after a sufficient amount of liquid has been sprayed, the curtain will become well formed and the spray head returned to the 3 o’clock position. This may take some practice, but can be done.
Spray the water at 20 psi using an Sprayco 8002 TeeJet spray tip or similar.
Allow rotation to continue for a minimum of four minutes after all water is added..
Spray the Sulfonic Acid.
The brown sulfonic acid will neutralize with the soda ash to form a white anionic active LAS. Allow the batch to rotate until the sulfonic acid has reacted (brown is gone) and the batch has cooled down (under 100 deg F). Depending upon materials, this may take some experimentation. If the reaction is incomplete or the bed is too hot, spray a small amount of water to help the reaction or evaporate off to cool the batch.
Carefully add the STP. The safest way to do this is to stop rotation. However, many users will turn the drum rotation very slow and scoop the STP carefully in to the drum. Freshly made LAS can cake-up if left motionless too long. The STP will help hydrate the excess moisture and condition dry the product.
Remove the spray bar(s) and clean, keeping the rotation very slow. Pour the nonionic active into the agglomerator, or spray at 20 psi. Use a higher pressure if necessary. If adding nonionic by pouring, shut the rotation off for a very short time (a few seconds) to be sure the pouring is safe.
Place the silicate solution into the sprayer. Spray at 20 psi. Use a higher pressure if necessary.
Allow the agglomerator to rotate until the powder is dry. In some cases (a humid day, for example) use a handheld dryer or other heat source to help drying.
post agglomeration processing
Let the final product churn in the agglomerator until it is dry. If the batch is taken out before it is at dry, it can cake.
Before removing the batch, add any heat sensitive (check the temperature) or expensive minor ingredients to the conditioned batch. Let the drum turn a few minutes to mix the last ingredients
Particle size of the finished product is a marketing decision, but a product that passes through a 10 mesh screen (called -10 mesh), but will not pass through a 30 mesh screen (+30 mesh) is often considered a good start.
The oversize (+10 mesh) and undersize (-30 mesh) can be recycled into the next batch to avoid waste.