There are many kinds of flour used in Food Processing worldwide. Two of the most important are wheat and corn, but there are many other specialty flours as well. This wide variety makes it difficult to simplify the flour production process. However it is safe to say that all flour is milled, and when that milling process is dry, fine flour dust is created that must be removed from the air to protect the working environment and to minimize product loss from the milling operation. It is also safe to say that most flour is cleaned and formulated in air streams and the final product is often collected from these air streams using some type of air filter. Fabric bag dust collectors and baghouses are used extensively to collect nuisance flour dust from milling and transporting operations and to separate the final product from the process air stream.
Both of these applications are characterized by extremely fine particulate that puts extra demands on the air filter media. Oils and other formulation products added to flour compound the difficulty of the final product separation process by making the fine particulate sticky as well. The challenge is to provide air filter media that provides the fine filtration required at high production rates that will clean well and give the flour processor an acceptable bag life. And of course, all materials must be food grade.
On the liquid side, a large percentage of corn flour and meal is produced in wet milling operations. In a wet corn mill, the corn is soaked in water before being wet milled. The resulting slurry is then separated into cornstarch, gluten, corn oil, corn sweeteners and corn flour. During the wet phase, large rotary drum vacuum filters are used to separate gluten and starch from the slurry. Corn oils and corn sweeteners are usually polish-filtered in pressure leaf filters, and powdered carbon that has been used to decolorize the sweeteners is sometimes recovered and recycled using smaller rotary drum filters.
Some filtration operational problems solved by Menardi:
- High differential pressure
- Production loss
- Filter bag blinding
- Premature bag failure
Menardi provides fabric filters for all of the dry and liquid applications discussed above. Some Menardi products supplied to the Flour Processing Industry include:
- Mikrotex® expanded PTFE membrane laminate
- Mikro-Pleat™ Pleated Filters
- Micro denier felt filter bags
- PulsePro™ diagnostic system
- Field technical inspections
Example Dust Collection Application
A major flour producer needed to increase production, but did not want to make a significant capital expenditure. Menardi sales engineers helped the processor easily convert the existing baghouse from standard felt filter bags and cages to Mikro-Pleat™pleated filters, constructed of spunbond polyester.
The conversion allowed the processor to increase the throughput (production) with the existing baghouse. The spunbond polyester was also more efficient than the felt, reducing initial emissions and resulting in better filter cleaning. The longer filter life and the elimination of the cages reduced filter changeout time considerably. The labor savings alone was such that the processor's overall cost of ownership of the more expensive pleated filters was figured to be actually less than that of the previous felt filter bags and cages.