Agrofeed Ltd. KNOWLEDGE THROUGH FEEDING
BRIEF DESCRIPTION OF HOMOGENITY RULES IN COMPOUND FEED PRODUCTION
IMRE PINTÉR TECHNICAL DIRECTOR February, 2018
Export Business Division Dr. Péter Zoltán | export@agrofeed.hu | +36 30 2375991 www.agrofeed.hu
Feed mill technical conditions for homogeneous compound feed production It is always a vital question in each feed mill, what could be the proper premix (panel, premix, concentrate) concentration to purchase and to use, based to technical conditions in the feed mill, which allows to produce homogenous compound feed. Usually panel, premix producer companies having very precise and sophisticated machinery back ground which ensures to produce highly concentrated panels (0,1-0,3%), premixes (0,5-1,5%), complete premixes (2,0-4,0%) or concentrates (5,0-30,0%). The feeding knowledge and technical level, production capability of compound feed factories is different worldwide, according to the original production aim, supplier of concept and equipment, age of feed mill, original investment and of course from maintenance and reconstruction. Each feed mill professional and management staff has to decide, based to the local circumstances, what kind of premix concentration (panel, premix, concentrate) is the most feasible for them, and according to that they need offer and supplier, which is able to fulfil all raw material and quality requirements and providing the best financial solution. It is same mistake to purchase too concentrated premix, which cannot be mixed homogenously in the feed mill’s technical condition, as to buy too diluted products which contains locally available (usually cheaper), not quality sensitive raw materials, which are more feasible to buy locally and to mix it to the compound feed. Of course, the technical capability of the feed mill basically determines the possible options or concentration range of products to purchase to secure the homogeneity of produced compound feed with the lowest possible direct cost. Agrofeed is ready to provide technical service for its customers to find the optimal solution for their purchasing strategy which equally provides optimal technical and financial solution for them.
Essence of homogeneity A mixture would be “homogeneous� if all the ingredients in each sample were present in the exact proportions specified by the recipe. However, with mixtures made up of mealy and granular ingredients such as are encountered in the feed manufacturing industry is not possible.
Essence of homogeneity testing Homogeneity or mixing accuracy of a mixture indicates how efficiently a single ingredient is distributed among the totality of the other ingredients. Just one component is identified in all samples, serving as a representative for all others. It might be already in the mixture or can be a special indicator added for this purpose.
Mixing conditions of a two-component mixture
Catching the first optimal mixing time An excessive mixing time causes a negative effect producing segregation. This phenomenon cannot be adequately explained by scientific methods. The reason probably is that a circle is created between mixing and segregation. The first optimal mixing time can only be determined on the basis of homogeneity (CV) tests.
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CV (%)
FIRST OPTIMAL MIXING TIME FOR COMPOUND FEED (8,8%; 5,5 min)
t (min)
Principle of sequential ingredient filling into the mixer It is desirable to achieve the implementation of mixer filling by means of “sandwich principle�, i.e. premix must be added at about halfway of filling of all other ingredients. Otherwise, if premix addition is too early some of its components may remain on the bottom of the mixer or if premix addition is too late some of its components may remain in the upper area of the mixture (in both cases proper mixing may be damaged).
VOLUME OF INGREDIENTS
FILLING BY HAND ADDITION OR BY WEIGHERS
Beginning of mixing time Ingredient 1 Ingredient 2 Ingredient 3
Premix
Ingredient 5 Ingredient 6 Ingredient 7
TIME OF MIXER FILLING
If we add into the mixer separately premixes (twin bag concept), when a part of premix (concentrate) is produced separately and contains the most quality sensitive, small quantity components (for example 0,5-1,25%) and the other part containing macro elements and other ingredients are available and more feasible to produce locally (1,0-2,0%), must be sure that the mixer is mixing evenly and able to produce homogenous compound feed.
CV values in accordance with Hungarian regulations Names of feed groups Blends and premixes Complete premixes and additives Concentrates and supplementary feeds Compound feeds
CV% maximums 5% 8% 10% 12%
Premix concentration in compound feed Right premix concentration in compound feed can be determined by homogeneity measurement on the bases of such an ingredient, which is found only in premix. As long as the result does not exceed 12% of the CV value the premix concentration is interpreted as proper.
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It should be noted the higher the premix percentage the lower the CV value in compound feed or in other words higher premix ratio results better feed quality. Though present day manufacturers guarantee a dilution of 1:100 000 (10 g per 1000 kg) for mixers this value can only be achieved nearly in laboratory conditions. Dosing a component less than 0,5% of a mixture or 0,2% of a single ingredient desirable to avoid even into the best mixers because of mixing accuracy influencing factors. Some possible ratings of compound feed plants in terms of premix applicability Plant capabilities Premix ratio CV value in mixer Special 0,5% not exceeding 12% Excellent 1,0% not exceeding 12% Very good 1,25% not exceeding 12% Good 2,5% not exceeding 12%
Factors influencing mixing accuracy
Proportioning of components
Accuracy of scales
Product properties
Particle size (in a range of approx. 3 mm but 65-70% within 1 mm)
Accuracy of dosing elements
Particle shape Bulk density (in a range of approx. 0,5 kg/dm3)
Size of component
In % of the total batch
Type of mixer
Depending of mixer design Depending on mixing tools
Mixing time
Horizontal mixers Vertical mixers
Liquid addition
Lump formation
The more similar the various ingredients are regarding their bulk density, particle size and flowability the better the mixing quality and stability of a mixture.
Example of CV calculation To obtain a true result a minimum of 10 samples of approx. 50 g have to be taken. A sample of 10 g must contain at least 400 particles. In 10 samples the proportions xi of an indicator are detected in mg. xi (mg) Δxi (mg) (Δxi) (mg2) 110 13 169 112 23 529 130 33 1089 120 23 529 80 -17 289 140 43 1849 70 -27 727 100 3 9 40 -57 3249 60 -37 1369
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Σ(Δxi)2 =9810(mg2)
ÎŁxi =970(mg) Where,
n=10 ÎŁxi x= =
970
đ?‘›
đ?‘†=√ đ?‘‰=
= 97 mg
10
Σ(Δxi)2
(n−1) đ?‘†Ă—100 đ?‘Ľ
9810
=√
=
mg = 33,015 mg (Standard Deviation)
9 33,015Ă—100 97
= 34,04 % (Coefficient of Variation)
160 140 140
130 120
120
110
112 100
100 80 80
70 60
60 40 40 20 0 Sample 1 Sample 2 Samlpe 3 Sample 4 Sample 5 Sample 6 Samlpe 7 Sample 8 Samlpe 9 Sample 10
In summary, the accuracy of this mixture with a coefficient of variation of 34,04 % would be extremely unsatisfactory.
Recommended mixing times for some types of mixers Conical
U-shaped
Circular
Special shape
Pear-shaped
Vertical screw
Horizontal Single shaft ribbon
Horizontal Twin shaft 28 paddles
5-20 min
4-5 min
Horizontal Single shaft ribbon or paddle 3-4 min
Horizontal Single shaft paddles 1,5 min
1-2 min
4-6
To summarize key terms of the right quality and homogenous compound feed are as follows •
Important prerequisite of homogenous compound feed production to be able to provide for every species and age group demand is that all ingredients of required feed formula must be added to the mixer precisely as possible. The measured raw materials must be added first into a collecting bin and from that to the mixer. Installation of bins before and after of mixer is suggested in technology to ensure safe and continuous operation.
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Premixes, complete premixes, medicaments, and other small quantity, but vital ingredients manually pour directly into the bin before the mixer or into the mixer, so that these components be possible placed midway between the other raw materials. Our feed mill mixer manufacturer’s recommendation will give the correct smallest quantity of ingredients which can be homogenously mixed in our mixer. Based to this recommendation can be decided the concentration of purchased (produced) panel, premix, complete premix, which contains all quality and quantity sensitive ingredients, like vitamins, micro elements and other feed additives. It is important preparatory step in the feed mill the chopping, grinding of ingredients to have nearly identical particle size to add to the compound feed. The larger the individual components physical property of differences, the more difficult the homogenous feed production. Significantly different volumes, grain size of the ingredients it is possible the danger of segregation. We recommend using a 3-mm sieve during the grinding, although this may depend on particular demand of species/age group and from the compound feed processing (mash or pellet). The tendency of the components to ensure adequate mixing may affect even with uniform grain size the volume and specific gravity of raw material, the form of particles, and coefficient of friction (surface roughness/smoothness). The component’s sedimentation, classification can be caused by the mixer design, improper filling measure in addition to features already mentioned. In the process of mixing technology, it is very important to follow the prescribed mixing time to the mixer type and correction according to homogeneity test results. As less mixing time is no longer recommended. This time cannot contain filling and emptying time of the mixer. Periodic laboratory control is expedient and recommended of the compound feed homogeneity. A sample numbers of 10-12 pieces, possibly from the most divers points of the mixer or from different bags after bagging. The granulated (pellet) or crumbled compound feed provide good support to get the animals to feed all the little particles of homogenously.
Győr, February, 2018
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Agr o feed Lt d. KNOWLEDGE THROUGH FEEDING
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