ARTICLES

A Perspective On Mixing And Mix Uniformity: Part 5 - Compliance

Compliance

Feed manufacturers should not have difficulty meeting requirements established by the regulatory agencies if they adhere to rigid cleaning and operational procedures. When micro-ingredients and premixes are being added, dust collection systems or other air suction systems should be carefully balanced such that a minimum of air is drawn from the mixer. Fortunately, regulations have, in the past, provided a broad range of concentrations in between which the feed manufacturer may operate. However, in light of today’s improved detection techniques and consumer concern and awareness of potentially harmful drug residue problems, such allowable variations are being reduced. Most feed producers will not be satisfied with producing a feed having as broad a range as was once permitted.

The mixer should, of course, have good mixing efficiency, and allowing for sufficient time to thoroughly blend the feed is an absolute MUST.

When using antibiotics and other micro-ingredients in mixes which are prepared intermittently for poultry, swine, sheep, and cattle, the manufacturer should be sure:

1. That the mixer internals are clean and that it is cleaned out thoroughly between the mixing of the different rations. This means stopping the mixer and removing excess materials in filler tubes and cut-in hoppers.
2. That the mixer is grounded to bleed off static electricity.
3. That regulatory requirements are followed for:
a. Cleanout of accessory equipment
b. Labeling
c. Recheck of ingredient weight and inclusion
d. Sampling, etc

Operational Comparison Of Standard Horizontal Batch Mixers And Drop- Bottom Horizontal Batch Mixers

Operational procedures of the drop-bottom unit is very much like the operation of a normal single or multiple discharge mixer, but it has an added advantage in that it discharges most rapidly; as fast as ten seconds for opening, discharging, and closing of doors. The mixer is completely emptied and clean with very little possibility of contamination. This rapid discharge feature reduces the total mixing cycle time, and, since the feed mill capacity is based largely on mixing capacity, can possibly increase plant capacity through savings in discharge time.

Sequence Of Ingredient Addition To Drop-bottom Mixers

We know that there is a decided advantage in following a particular sequence when charging ingredients into the mixer. With the drop-bottom feature you do not have discharge pockets that can possibly catch a few pounds of the first ingredient that is put into the mixer and hold it unmixed. There are no pockets, but a smoothly contoured bottom formed to the contour of the ribbon itself. This further reduces the possibility of segregation and "dead spots" .

Cleaning And Maintenance Requirements

Periodic cleaning of the drop-bottom mixer is no more difficult than the normal periodic cleaning of a standard single or multiple discharge mixer. This can be accomplished through the top or by installing access panels in the side of the catch hopper below the mixer and cleaning it from the bottom with the doors swinging open. Normal cleaning of this unit in dry feed mixing consists of removal of strings that might catch on the ribbon assembly. The only other additional maintenance that would be required would be on the air cylinders themselves and, with proper installation of air supplies with traps and filters, this should be no problem at all.

Noncontamination Feature

The self-cleaning non-contamination feature is a basic point in favor of this particular type of unit. The possibility of contamination must always be considered when using drugs, and we know there are many places in the feed plant where contamination can occur. By eliminating the problem here, one contamination worry is removed.

I might mention, going a bit further, that if you are using bucket elevators to elevate your mixed feed, you can eliminate another source of contamination by equipping your elevator legs with automatic boot cleanout units. These, too, can be integrated into your semi- or fully- automatic batching system to cycle between each batch if desired. Another way to reduce contamination is to use a gravity flow system wherever possible.

With today’s high energy specialized feeds, with the necessity for feed mill efficiency, and with contamination being the problem it is, we feel that the drop-bottom mixer will prove more and more important in modern feed manufacturing operations.

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