Straw pellet mill is a kind of pellet press used to make pellets from biomass materials for heating purposes. The raw material can be wheat straw, rice straw, and other similar agro waste.Straw is a generic term used to refer to residues that remain from harvesting grain plants such as rice, corn and wheat among others. This important agricultural residue is quite popular in Europe where an estimated 23 million tones of straw is produced each year across the 15 states. Straw pellets are special products produced from straw and has applications ranging from heat production to animal feeds and animal bedding among others. In order to make the pellets from raw straw, a number of procedures must be performed. This is because the original residue is composed of different compounds that include cell (80-90%) and lumen (10-20%). The internal composition includes silica and extractives all which are water soluble. Here is a detailed step-by-step description of how to make straw pellets.
How To Make Straw/Grass Pellets?
★ Preparation of raw materials
The harvesting process leaves straws mixed with dusts and other alien materials like stones, metals and plastics. These foreign components have the potential to damage pelleting mills and also lower the quality of the pellets. They must therefore be removed.
Straw biomass is basically a tube-like material that needs to be crushed to the required size that can then be used in the aforementioned applications. Grinding mainly involves cutting and chopping the straw the appropriate dimensions usable in pelleting machines.
This process of making straw/grass pellets is often bypassed yet is still worth mentioning as part of straw pellet formation. Straw is delivered containing about 15% moisture content which is ideal for producing pellets. When saw dust is also used, then drying is added to the process.
This is basically the process of increasing straw hardness to the desired state. It involves application of steam or water as well as binding agents and additives. Conditioning is necessary for achieving right temperature that allows malleability and melting of the lignin (which is found in raw straw) to act as the binding agent. Increasing hardness prevents excessive abrasion when pelletizing.
Straw/grass pellet mill is the main phase of producing straw pellets. During this proves, consider aspects of moisture content in the straw,fibre strength, particle size and natural binders. All these influence the pellet quality. It is also important to prevent pellet breakage, overheating and pellet die blocking. These challenges may lead to increased energy costs, damaging the grass pellet mill and poor pellet quality. It is thus important to use high quality straw and also use thicker pellet die to increase compression length and yield favourable quality.
★ Cooling and Screening
After pelletizing, the straws will generally be hot and soft. They should then be cooled down to attain desirable hardness while refining fine particles. The final product will have reduced moisture content yet depicting increased bulk density. The moisture is often reduced from the 15-20% to below 10% while density rises from 130 to about 600 kg/m³.
What Raw Materials can be processed into straw/grass pellets?
There is a wide application of raw materials, such as wood, sawdust, straw, chaff, bamboo shaving, peanut shells, bagasse, alfalfa and other raw materials, etc. All the forestry and agricultural scraps can be made into small feed or fuel pellets. But different materials have different request to moisture and size. Generally, moisture of raw material is near 15%. Under this situation, pellets produced will have perfect quality. But materials whose lignin or sugar content is high will need less moisture. For the size of raw materials, it should be no longer than the diameter of die holes. For example, if the diameter of die hole is 6mm, while the size of raw materials is near 8mm, there will be accumulation or even damage inside the pellet mill. Anything you can think of raw materials, our biomass pellet mill can help you achieve the aspiration of pelletizing.
Benefits of Straw/Grass Pellets
1. The growth and utilization of the fodder are greatly influenced by seasons. Forage turn wither and yellow with less nutrients in winter . Yet, forage grow vigorous with more nutrients so that livestock can’t eat them up in warm seasons. So, in order to make full use of grass in the warm season to make the effect to come true, the livestock and poultry can be fed in winter with the grass pellets conserved in process of mowing, drying, crushing.
2. High transform rate. Feeding the livestock and poultry with the grass feed pellets in winter, we can gain more meat, egg and milk with less forage.
3. Small volume. Grass pellet is only around 1/4 of the raw materials in volume in favorable for storage and transportation. In addition, less dust is beneficial to the health of human and animals.
4. To increase palatability and improve the quality of forage.
For instance, sweet clover possesses a flavor of coumarin which livestock more or less don’t like it. However, it becomes another forage with a strong palatability and high nutritional value.
5. To spread the source of fodder
such as caragana, optimal quinoa, hedysarummaxim. Etc which have the thick branches turn to the favorable forage once processed into the grass pellets after crushing. Moreover, secondary product of other crops such as abortive shell, straw as well as all kinds of leaves also can be processed into grass pellets and feed livestock and poultry.
Technical Parameter of Grass Pellet Mills