06. 28, 2020
The single feed pellet with different color which appears in the granulation process commonly known as "flower feed". This situation is relatively common in the production of aquatic feed, mainly showed as the color of individual pellets extruded from the mold is darker or lighter than other normal pellets, or the surface color of single pellet is inconsistent, thus affecting the appearance quality of the whole batch of feed.
The reasons for this phenomenon are as follows:
a）The ingredients of the feed formula are too complex, the raw materials are too many, the mixing is not uniform, the moisture content of the powder before granulation processing is not consistent.
b）The moisture content of the raw materials used for granulation is inconsistent. In the aqua feed production process, in order to make up for the loss of moisture of raw materials after pulverizing, a certain amount of water should be added into the mixer for mixing, and then go to the conditioner for conditioning. Some feed factory use simple process, they directly add a certain amount of water into the mixer rather than using a special sprinkler to spray evenly, so it is difficult to make the moisture in feed can be evenly distributed after mixing. When this kind of mixed material enters the conditioner, it is impossible for the conditioner to further distribute the moisture evenly in a short time. Under the action of steam, the curing effect of each part of the feed after tempering is not consistent, so is the color change after pelleting.
c）There is re-granulation feed material in the granulating bin. The pellets can become the final products only through cooling and screening. the fine powder or small granules will often enter the granulating process for re-granulation again, usually go into the mixer or pre-pelletizing bin, because this is the second time of conditioning and pelletizing for the material, if it can not be mixed with other material evenly or there are small pellets after conditioning, it will appear flower feed for some feed formula.
d）The degree of finish of the inner hole is not uniform. Because the die hole finish is not consistent, the resistance and extrusion pressure for the pellets is not the same, the color change is not consistent. In addition, there are burrs on the hole wall of the ring mold, which will scratch the surface of pellets during extrusion, causing the surface color of individual particles to be different.
For the four causes listed above, the improved method is clear, which is mainly to control the mixing uniformity of each component in the formula and the mixing uniformity of the added water. Improve the tempering performance which can reduce the color change; Control return-material, for the formula which is easy to produce "flower material", do not use return material to granulate directly as far as possible, the return material is better to mixer with raw material and grinded again. Adopt the ring mould with guaranteed quality, control the finish of the mould hole, and grind the mould hole before use if necessary.
It is recommended to use FDSP's SZLH508DDC+ B2 series high-grade ring die pellet mill. The main machine is equipped with a two-axis differential speed conditioner and two extended jacket conditioner. The tempering time can be as long as 60-120 seconds, and the tempering temperature can reach above 100℃ with evenly conditioning performance. The contact area between the material and steam is greatly improved by multi-point steam intake, so as to improve the curing degree of the material and improve the tempering effect. Digital display instrument and temperature sensor can display the tempering temperature, which is convenient for users to control at any time.