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What Are Pellets Made Out Of?

By Jack Huang    Nov 09, 2017

what are pellets made out of
 

The pellet is made of biomass materials with pellet machine. The pellet is born in the tide of biomass energy. As hot-sale clean energy in the market, pellets not only give more options for using energy, but also provide a new way to make money. Pellets have a lot of applications like biofuel, animal feed, electricity generation, fertilizer, and etc. Biofuel is a common application of pellets.

Why we choose wood pellets to replace traditional fuels? Beside the environment friendly features, there are various advantages of pellets, such as turn waste into wealth, easy to get raw materials, easy to process, easy to transport, higher combustion efficiency.

Raw materials for pellets making

Raw materials for pellets making have wide ranges, including plant, animal and microorganism, such as lignin, farming industry scraps, forestry and agricultural residues, livestock manure and waste produced in the Livestock husbandry production. Raw materials of pellets contain cellulose, hemicellulose, and lignin. Due to the loose structure and low density, materials will pass through three stages include position rearrangement, mechanical deformation and plastic deformation. Inelastic cellulose and viscoelastic cellulose spiral and strand each other, which made the material smaller and denser.

Generally, there are some differences between wood pellets and feed pellets.

Wood pellet

Wood pellet is commonly made of wood chip, sawdust, shavings, bark, crop straw, and other biomass materials. By the type of wood, raw materials of wood pellet can be divided into hardwood and softwood.

  • Hardwood has high density, such as Birch, beech, poplar, yew, hard maple, elm, etc. In general, the hardwood has low water content, compared to softwood, it has longer burning time.
  • Softwood usually refers to gymnosperm like Pine, rosewood, cedar, fir, spruce, etc. Although softwood has shorter burning time compared to hardwood, it can burn more sufficiently.
  • In conclusion, every kind of wood has own advantages. In the processing of wood pellet production, water content of raw materials should be controlled by 10-15%. Besides, heat and pressure change the structure and density of materials in the production, so hardwood and softwood of same weight will have equal combustion value.

Feed pellet

Raw materials of feed pellet usually include core, bean pulp, straw, rice husk, and etc. According to the applications, feed pellets can be classified into fish pellet feed, feed pellet for rabbit, feed pellet for pig, and so on. There are two questions for client who firstly come into contact with feed pellet.

  • Q1: Why use feed pellet replace traditional feed? What are differences between them?
            A: The feed pellet has advantages like comprehensive nutrition, improve digestibility of feed, and decrease the picky-eaters of animal, easy to transport and store, etc. So that feed pellet is popular among farmers.
  • Q2: Why add grease into raw materials? What’s the function of grease?
            A: Generally, except the corn straw, bean pulp, vitamin, salt, raw materials of feed pellet contain grease. The grease of feed pellet has two main function: 

Oxidation

Unsaturated fatty acids in fat contain double bonds, so it can through reduction, and change into saturated fatty acids. Dietary fats of ruminants can occur H effect in the rumen, saturated fatty acid content of body fat is higher.
 

Hydrolysis

fat will hydrolyze under the condition of acid or alkali, the hydrolysis products are glycerol and fatty acids, animal and vegetable fats hydrolysis was catalyzed by lipase. Free fatty acid produced by hydrolysis is odorless and tasteless, but low-degreed fatty acid has strong smell like butyric acid and acetic acid. Various kinds of bacteria and mold can produce lipase. When feed pellets have inappropriate storage, the fat of pellets is easy to hydrolyze, which decrease the quality of feed pellet.

The degree of rancidity of fat is in the form of acid value. The acid value refers to required amount of KOH in the 1g fatty acid neutralization reaction. When the acid value of fat is bigger than 6, it will have a bad influence in the health of animals.