Husk

Types of rice husk

Rice husk is the outer, inedible part of grain rice and is a major by-product of rice cultivation. It has a hard texture and is lightweight. Rice husk is an important biomass fuel, and burning rice husk generates enough heat to produce steam for electricity generation or rice mills. The ash of rice husk contains silica, which is useful for making cement. Rice husk has a number of applications.

• Rice husk power generation

  About 35% of the energy generated from burning rice husk is used to produce electricity. The remaining energy is used to generate steam, which is used to process additional rice. A small amount of electricity may be sufficient to meet the needs of the rice mill itself. A larger amount of electricity may be distributed through a power purchase agreement in the local power grid.

• Replacement of plastic

  Rice husk fibers mixed with other natural fibers can be used as an environmentally friendly alternative to plastic to create biomass material. This material is suitable for making composite materials for automotive interior trim, such as door trim and dashboard components. It is also used to replace plastic toys. Rice husk can also be manufactured into biodegradable rice husk cup and other items.

• Silica from rice husk ash

  The burning of rice husk produces rice husk ash, which in turn contains a large amount of amorphous silica. Silica is widely used in the rubber and cement industries. Adding amorphous silica increases the firmness of cement and enhances its durability. Rubber products with silica have high tensile strength and resistance to aging.

• An agricultural fertilizer

  Rice husk has a high carbon to nitrogen ratio and is often used as a soil amendment for mushroom cultivation. This not only improves the quality of the rice husk but also improves the fungus-grown mushrooms and reduces the rice husk's carbon footprint. Rice husk ash is commonly used as an agricultural fertilizer, providing rice plants with a wealth of silicon and enhancing resistance to disease and pest infestations. This facilitates sustainable agricultural development.

Specification & Maintenance

Rice husk has a wide range of applications, which means its demand is growing by the day. People need to know more about the types and specifications so they can fulfill the demands of end-users and business buyers.

When people think of rice husk types, they typically think of two main kinds: the burned and unburned versions. The latter is light in color and somewhat bulky. The traditional uses include animal feed and fertilizer. The burned version is darker, denser, and blacker. It comes about after burning rice husk in a creative kiln. Manufacturers often use this version of rice husk to produce biochar.

When it comes to rice husk specification, people usually think of its particle sizes and moisture content. The traditional rice husk is quite coarse and fibrous because it protects each grain of rice. Its average particle size is typically bigger than the average size of rice grains. When it gets processed into biomass fuel or rice husk ash, the particle size becomes smaller.

The moisture content of rice husk is 20-22% when it's removed from the milled rice. Many storage and processing facilities aim to get the moisture content down to 14% to avoid mold growth and increase burn efficiency.

Even though rice husks don't need a lot of maintenance, they do need some care when they're being stored or transported. The main goal is to prevent degradation and protect the quality. Here are some practical tips for maintaining rice husk.

• Safe storage: Store the rice husk in a dry place that's away from any flooding or water to protect it from mold growth. Use waterproof tarps and husk bags to cover it when transporting it. Aim to keep the moisture content below 14% in order to increase longevity and avoid fungal infestations.
• Frequent air circulation: Excessive air can lead to combustion, so remember to ventilate the storage facilities often. This helps in keeping it dry and reducing the buildup of carbon dioxide and humidity. The regular airflow also prevents fungal infections and decaying.
• Pest Control: Check the rice husk every now and then and look for signs of infestation or pest damage. Use natural and safe insect repellents to keep skunks, rats, and weevils away.
• Maintaining quality: Avoid mixing the rice husk with low-quality ones to ensure the end users enjoy a great experience. Handle the rice husk with care so it doesn't get contaminated by chemicals or other foreign materials.

Scenarios of husks

Due to their unique features and advantages, husk products have a wide range of uses in many industries.

• Packaging industry: Husk products are used as cushioning materials in fruit packaging. Using fruit packaging made of husks can reduce the risk of injury to fruits. Additionally, this strategy has the potential to cut down on the use of plastic packaging and produce a more environmentally friendly option for consumers.
• Agriculture: Husk products are widely used as mulch and biomass in agriculture. As mulch, they can keep the soil moist, suppress weed growth, and improve crop yields. As biomass, they can serve as raw materials for organic fertilizers. Meanwhile, thanks to the addition of husk-based organic fertilizers, soil quality can be significantly improved.
• Renewable energy: Husk products are used as raw materials for biomass power generation. Biomass power generation utilizes the energy produced by combustion when biomass raw materials such as husks are abundant. This provides a stable energy supply for the development of renewable energy.
• Textile industry: The fiber extracted from the husk can be used to weave durable fabrics in the textile industry. These fabrics can be used not only to make traditional garments but also to use industrial and specialty products. Moreover, products made from husk fibers are strong and wear-resistant, making them suitable for use in harsh environments and heavy-duty scenarios.
• Automotive industry: In the automotive industry, husk products can be used to make interior parts such as door cards and headliners. These parts are lightweight and have sound insulation and vibration damping properties, which can improve the comfort and riding experience of the vehicle.
• Construction materials: Husk products can be used as building materials for houses and furniture. For example, hemp hunk houses are not only sturdy but also have good thermal performance. In addition, hemp has the property of absorbing moisture, which can help regulate indoor humidity.
• Eco-tourism: Husk products can be used for eco-tourism. For example, in some eco-tourism sites, husk products are used as the main building material for cottages and pavilions. This not only reflects the concept of sustainable development but also gives tourists a closer connection to nature and an authentic rural experience.

How to choose rice husk

• Demand analysis:

  It is important to determine the application demand of buyers before purchase. Some uses as biomass fuel need to burn efficiently, while others as animal bedding do not need burning efficiency but need to be dust free. Different processing methods meet different application demands.

• Supply source:

  Since rice husk is area-specific, the supply source will have a huge impact on the price. If the end application is far from the source of rice husk, then the transportation cost will be significant. It is more economical to apply it locally as biomass fuel.

• Quality:

  Rice husk has many varieties, and quality will vary according to the type of rice and recovery process. As biomass fuel, burning calorific value is the main concern. When purchasing as animal bedding, one should pay more attention to cleanliness to reduce the risk of disease in animals.

• Servicing:

  When making a commercial purchase, it is important to get value for money and good after-sales service. When storing or transporting rice husk, it is important to have a suitable storage container. One should negotiate with the supplier for discounts on bulk purchases and for suitable storage and transport containers.

Husk FAQ

Q1: What is the difference between husk and stalks?

A1: The husk is the outer covering of grains and seeds, while stalks are thin, long, thread-like parts that connect grains or flowers to the ground.

Q2: What are the pines and straw husks?

A2: The pine husk refers to the outer part of the pine tree, which usually stays on the tree for a long time, while straw husk refers to the part that covers the grain after harvesting. When the straw is processed, it can be made into straw husk pellets for storage and transportation.

Q3: What are the uses of husks?

A3: Some botanical husks, like rice husks, are too hard to be used for felting and stuffing, but they can be burnt for energy. Others, like cotton and corn husks, can be used for various crafts. Husk fibers extracted from hemp and coconut are strong and, after processing, can be used in the construction industry. Husk from crops is often used as animal bedding, parchment in the food industry, and cleaning products.

Q4: What is the trend of the global husk market?

A4: The global husk market is growing by 6% annually as more and more uses are found for it, particularly in the construction industry. India and China's demand for biofuel has also caused the global husk market to expand.