How to Properly Prepare Raw Material for Briquetting: Particle Size, Composition and Homogeneity

The quality of finished briquettes depends not only on the specifications of the briquetting press but also on how well the raw material is prepared. Particle size, moisture content, composition and homogeneity affect the pressing process, the density and mechanical strength of the finished product, as well as the operational stability of the equipment.

For woodworking companies, briquetting provides an efficient way to utilise sawdust, wood chips and wood dust generated during production. However, before feeding the material into the press, it is important to ensure that the raw material meets the requirements of the briquetting process.

Let us look at the main stages of raw material preparation for briquetting.

1. Particle Size: Why Choosing the Right Fraction Matters

Particle size and shape are among the main factors affecting briquetting quality. Particles that are too large can make uniform material compaction more difficult. This is particularly relevant for long, fibrous and tangled wood shavings, which may require pre-shredding.

On the other hand, excessive size reduction is not always justified. It increases the energy required for raw material preparation, while a finer particle size does not automatically guarantee higher briquette strength.

To achieve good-quality briquettes, it is important to ensure a suitable particle size distribution, also known as the granulometric composition of the material.

What should be taken into account:

• Larger wood chips and long shavings should be pre-shredded if necessary.
• Particle size must comply with the requirements of the specific briquetting press.
• Particles that are too long and fibrous may interfere with uniform material feeding.
• Mixing particles of different sizes is acceptable if it ensures stable pressing and the required briquette quality.

RUF briquetting presses are designed to process wood dust, sawdust and wood shavings. According to the manufacturer's technical information, the size of wood particles should not exceed 50 mm. Finer material generally allows briquettes with a smoother surface and more uniform edges to be produced.

It is important to understand that 50 mm is the maximum guideline for the relevant equipment series, not the recommended size of every individual particle. The optimal particle size should be determined according to the specific raw material and press model.

2. Raw Material Moisture Content: An Important Briquetting Parameter

The moisture content of the raw material affects the pressing process, as well as the density and mechanical strength of the finished briquettes. Excessive moisture or a moisture level unsuitable for the selected technology can reduce product quality and production efficiency.

For RUF briquetting systems, the preferred raw material moisture content is below 12%, with a maximum guideline of below 15%.

For more information on how raw material moisture content affects briquette quality, energy consumption and the economic efficiency of production, read our separate article: How Raw Material Moisture Content Affects the Economics of Briquetting.

3. Raw Material Composition: What Materials Can Be Used for Briquetting?

Various types of wood residues can be used for briquette production. The most common types of wood raw material include:

• sawdust;
• wood shavings;
• wood dust;
• fine wood particles;
• shredded wood chips.

It is important to consider that different materials have different densities, moisture contents, fibre structures and chemical compositions. Therefore, identical equipment settings do not necessarily produce the same results when pressing different types of raw material.

Particular attention should be paid to foreign materials and contaminants. The raw material should not contain metal fragments, stones, plastic, sand or other foreign materials. Such contaminants can reduce the quality of the finished product, increase equipment wear and cause operational problems.

If a company plans to use several types of raw material, their compatibility should be assessed in advance and suitable mixing proportions established.

4. Raw Material Homogeneity: The Key to Stable Production

Even when raw material meets the requirements for moisture content and particle size, significant variations in its composition can affect the stability of the briquetting process.

For example, if one batch mainly consists of fine, dry sawdust while another contains larger, wetter wood shavings, the material will behave differently during pressing.

Changes in raw material properties can affect:

• the density of finished briquettes;
• their mechanical strength;
• the stability of the pressing process;
• equipment productivity;
• the amount of defective products and waste.

To ensure raw material homogeneity, the following practices are recommended:

1. Separate raw materials by type and origin wherever possible.
2. Monitor the moisture content of individual batches.
3. Avoid significant variations in particle size.
4. Maintain consistent proportions when mixing different materials.
5. Ensure an even supply of raw material to the press hopper.

A consistent raw material composition helps reduce variations in finished product characteristics and makes production process control easier.

5. Main Stages of Raw Material Preparation Before Briquetting

Depending on the initial condition of the material, preparation may involve several successive operations.

1. Sorting and cleaning. Removal of foreign objects, metal particles and other contaminants.
2. Size reduction. Reducing the size of larger particles and processing long or fibrous shavings when required by the raw material characteristics and equipment specifications.
3. Screening. Separating the material according to particle size. This operation helps control the particle size distribution and remove unwanted oversized particles.
4. Drying. Reducing the moisture content of the raw material to a level suitable for the selected pressing technology.
5. Mixing and storage. When using several batches or types of raw material, it is necessary to maintain a consistent mixture composition and ensure an even supply of material to the press.

Not every company needs to install all the equipment listed above. The composition of the preparation line depends on the initial condition of the raw material and the requirements of the specific production process.

6. Practical Example: Wood Raw Material Preparation at Avoti in Latvia

A good example of comprehensive wood residue preparation for briquetting is the project implemented by RMP at Avoti, one of the largest solid wood furniture manufacturers in the Baltic States.

The company required a solution for processing large volumes of wood residues generated at two production facilities. As a result, a fully automated briquetting line was designed and implemented, covering the entire process from wood residue shredding to finished product packaging and robotic palletising.

For more information about the project, read our article: Implementation of Innovative Technologies at AVOTI.

7. Why Is It Important to Test Raw Material Before Purchasing a Briquetting Press?

When selecting equipment, it is not enough to focus solely on the stated capacity in kilograms per hour. Actual productivity depends on the characteristics of the raw material, including its type, moisture content, particle size and bulk density.

For example, the same press may achieve different productivity levels when processing wood dust, fine sawdust or larger wood shavings.

Therefore, before purchasing equipment, it is important to provide information about the raw material and, whenever possible, conduct a test using the actual material.

RMP offers briquetting tests using the customer's own raw material. The test results make it possible to assess the characteristics of the produced briquettes and determine the most suitable technical solution.

Raw Material Preparation – The Foundation of High-Quality Briquetting

Proper raw material preparation is an essential part of efficient briquette production. Controlling particle size, moisture content, composition and homogeneity helps ensure a stable pressing process and achieve the required product characteristics.

Before selecting a briquetting press, it is important to assess not only the quantity of available production residues but also their actual properties. This helps determine whether pre-shredding, drying, screening or other raw material preparation equipment is required.

Planning to start producing briquettes from wood residues?

RMP specialists can help you select RUF briquetting equipment based on your raw material type, production volume and business requirements. Contact us to discuss the possibilities for processing your production residues.