How To Dry Out Sawdust? — 4 Options to Try

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Sawdust, the ubiquitous byproduct of woodworking and construction, typically ends up being overlooked and discarded. 

However, if you find yourself amidst a surplus of sawdust—whether you’re actively involved in woodworking or not—drying it out can pave the way for a plethora of innovative and functional applications.

In this guide, I’ve delved into four distinct methods to dry out sawdust effectively. By doing so, I aim to empower you to repurpose this often-wasted material in both inventive and practical manners. 

What Is The Significance Of Drying Sawdust?

Sawdust can be employed in numerous innovative ways, and its advantages go beyond being just a byproduct of woodworking.

With a little imagination and ingenuity, sawdust can be turned into valuable and versatile material, making it an eco-friendly and sustainable option that should not be disregarded.

In addition to its conventional use of cleaning up sawdust from woodworking projects, sawdust has many other practical uses. Sawdust is a safe and environmentally friendly alternative to chemical herbicides. You can use sawdust as a wood filler, and is useful for creating organic fertilizer.

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putting glue on sawdust

It is a versatile material that can be employed in construction to insulate the ceilings of houses or cottages. It is also quite surprising that some people believe sawdust has space-healing properties.

Facilities that manufacture pellets in bulk utilize a thermochemical method to dry sawdust and generate biomass, which has the potential to serve as a sustainable energy source by converting its energy.

Sawdust Dryers

Sawdust dryers are sophisticated mechanical devices created with the purpose of reducing the moisture content of sawdust by effectively drying it out.

These machines are typically used in industrial settings where large amounts of sawdust are produced. In addition, it comes in various sizes and styles, depending on the user’s specific needs, and typically is powered by electricity, gas, or diesel fuel.

Sawdust dryers employ various drying methods to decrease the sawdust’s moisture level from sixty percent to around ten-twelve percent. Thus, below are different techniques available to dry sawdust.

  1. Utilizing hot air, extract the moisture from the sawdust.
  2. While in motion on a conveyor or belt, dry sawdust utilizes fuel gas or hot air.
  3. Crush the sawdust to dry it out using hot air.
  4. Rotating the drum while exposing sawdust to hot air can cause the moisture to evaporate.
sawdust dryer

Rotary drum

The primary way to dry sawdust is through a rotary drum dryer. In an industrial setting, a rotary dryer decreases or removes the moisture content of a material being processed by directly exposing it to a heated gas.

The dryer consists of a sizeable, rotating cylindrical tube held by steel beams or concrete columns.

Moreover, the dryer is inclined, and the discharge end is positioned at a lower level than the material feed, enabling the material to move through the dryer effortlessly under the effect of gravity.

Furthermore, multiple welded shoveling plates on the inner surface of the cylinder assist in scattering and shifting the material, aiding in the dispersal and shoveling of the material to boost the interaction surface between the air and the layer of sawdust.

Process of Using a Rotary Drum to Dry Sawdust

  1. To begin with, obtain the sawdust that needs to be dried through a dust collection pipe system or by manual collection.
  2. The feeding hopper should be loaded with moist sawdust using a conveyor or an elevator.
  3. Following the feeding process, the material is exposed to hot air that enters the rotary cylinder.
  4. The drum is set in motion, and as a result of gravity, the sawdust within the cylinder moves from the top to the bottom end.
  5. At this moment, the sawdust is in contact with hot air.
  6. The sawdust is blended with hot air inside the equipment by using welded shoveling plates. This action enhances the interaction between the sawdust particles and the hot air, increasing drying efficiency.
  7. The sawdust advances forward due to the rotation of the drum.
  8. Eventually, the cyclone dust collector captures the sawdust blended with hot air.
  9. The water vapor contained by the sawdust exits through the top outlet alongside the gas exhaust.
  10. The rotary dryer released dehydrated wood shavings through its lower exit.
  11. Retrieve the dehydrated wood shavings from the outlet located at the bottom.

Aerodynamic dryer

sawdust in plastic bag

When drying sawdust, the aerodynamic dryer is the runner-up to the rotary dryer. The main purpose of an aerodynamic dryer is to eliminate the moisture from sawdust through the use of hot air.

This type of dryer functions by reducing the size of the sawdust into smaller fragments, which are then subjected to high-temperature air to extract the moisture content. Consequently, the sawdust is desiccated and dried, rendering it an excellent option for multiple industries.

In addition, aerodynamic dryers can decrease the moisture level in sawdust from sixty percent to roughly ten-twelve percent while simultaneously generating up to eight hundred kilograms of dried sawdust per hour.

Compared to the rotary dryer, the aerodynamic dryer can produce a much greater amount of dry sawdust.

Process of Using an Aerodynamic Dryer to Dry Sawdust

  1. Acquire sawdust through a manual collection or a dust collection system.
  2. Load the accumulated sawdust into the feeder.
  3. The sawdust drops down from the feeding hopper and enters the drying chamber.
  4. Use a hot stream with temperatures ranging from one hundred twenty to one hundred fifty degree Celsius to preheat the sawdust within the drying chamber.
  5. Alter the heated sawdust into a bed with characteristics similar to a fluid’s.
  6. Dry the fluidized bed to the desired moisture level by evaporating the excess moisture as it ascends to the necessary height.
  7. The sawdust material passes through a heated chamber until it becomes lightweight, then eventually carried away by gases that will be sent into the cyclone.
belt dryer sawdust

Belt dryer

Belt dryers are designed with modular components, allowing them to be used in large and small workspaces – making it easy to dry out sawdust.

Their flexible sizing means that they can be customized to fit the specific needs of any given area, making them a popular choice across various industries, from small-scale workshops to large manufacturing plants.

In addition, belt dryers are also known for their low energy consumption and operational costs.

They rely on a continuous conveyor belt to transport materials through the drying process, reducing the need for manual labor and shortening the overall drying time for large quantities of materials.

Process of Using a Belt Dryer to Dry Sawdust

  1. The belt dryer receives a steady stream of wet sawdust for continuous drying.
  2. Afterward, two conveyor screws disperse the damp sawdust uniformly on the belt and adjust it to a specific height. This step improves the contact area between the sawdust layer and hot air, increasing drying efficiency.
  3. The sawdust is conveyed to the belt feeder or drying area.
  4. A heating source that is accessible will be used to generate hot air within the heat exchanger unit.
  5. By passing hot air through the layer of sawdust, the drying tunnel decreases humidity and prompts moisture in the sawdust to evaporate, effectively drying it out.
  6. When calculating the required air supply, the entire length of the dryer is considered, and in the discharge zone, the volume of inlet air surpasses that of the outlet air.
  7. Optimizing drying can be accomplished by promoting effective airflow and ventilating the sawdust layers from the upper section downwards.
  8. The sawdust is screened to remove any fines.
  9. Hot air is removed by means of the conveyor belt.
  10. Once the belt dryer has reached its halfway point, a unit turning device is employed to move and blend the dried layer of sawdust.
  11. The mixing process eliminates moisture from both the upper and lower sawdust layers.
  12. This process results in a consistent and superior quality of dried sawdust.
  13. The dried sawdust is removed from the system once the drying process is complete.
  14. The sawdust drops down from the conveyor belt and onto the conveyor screw.
  15. To proceed with additional processing, retrieve the dried sawdust from the outlet.
flash dryer sawdust

Flash dryer

In a limited workspace, a flash dryer or pipe dryer can dry sawdust which can also be transformed into biomass [1] and fertilizers. It passes hot air through a narrow tube or pipe, quickly evaporating moisture from the sawdust.

Moreover, the sawdust is transported through the tube by a high-velocity stream of hot air. This process results in dried sawdust that can also be utilized as fuel for boilers or animal bedding.

In addition, the flash dryer can easily handle sawdust and efficiently reduce its moisture level between eight percent and seventeen percent. It is also an energy-efficient option that produces minimal noise which is easy to maintain and set up.

Process of Using a Flash Dryer to Dry Sawdust

  1. A conveyor mechanism can be used to feed moist sawdust through the pipe.
  2. At the same time, the heat exchanger will warm up fresh air.
  3. The heated air can now be directed to the dryer.
  4. The sawdust and heated air must be thoroughly mixed, ensuring the two layers have ample contact.
  5. At the same time, the water vapor from the sawdust evaporates and exits through the pipe of the outlet.
  6. Gather the dry sawdust from the discharge opening.

What Is the Amount of Time Needed to Dry Sawdust?

Using a rotary dryer, six hundred pounds of sawdust can be dried in six hours. Nevertheless, if a quicker drying process is necessary, I recommend utilizing a belt dryer or aerodynamic dryer.

drying time for sawdust

However, the exact duration that sawdust takes to dry depends on various variables. Moisture content, humidity levels, air temperature, and airflow are factors that significantly impact the sawdust drying process.

Other factors, such as the dryer type, machine efficiency, energy consumption, and the duration of dryer usage, can also contribute to the overall drying time. Hence, providing a definite answer to the drying duration of sawdust is not possible, as it can vary due to multiple factors.

How Does A Sawdust Dryer Operate?

The sawdust dryer’s operating principle revolves around using two-stage circulation systems for heat drying. The heat generated from the furnace is circulated to the dryer, which helps to dry the sawdust effectively.

Moreover, a sawdust dryer can typically decrease the sawdust’s moisture level from sixty percent to approximately ten-twelve percent. However, the extent of this reduction may vary based on the sawdust’s weight mass and the efficiency of the machine being used.

What Is the Process of Drying Woodchips?

The process of passive drying can be utilized for drying woodchips. This method involves stacking woodchips and left to dry naturally using the heat and air from the surroundings to eliminate their moisture content.

sawdust

However, the drying duration can be relatively long, depending on the initial moisture content of the woodchips, the weather conditions, and the size of the woodchips pile.

Another approach is to use active drying with the help of airflow. This method requires directing air over the woodchips to remove the moisture content.

In contrast to the natural approach of stacking the woodchips and waiting for the environment to dry them, active drying provides greater management over the drying process.

 

Conclusion

Given the resources at hand and specific requirements, there exists a spectrum of methods to effectively dry out sawdust. The natural approach stands out as straightforward and economical, though it’s worth noting that it’s a slower process and might not deliver the level of dryness you’re aiming for. 

On the other hand, opting for a kiln or oven guarantees rapid results, but it’s important to consider the higher costs and necessity of specialized equipment.

Turning to dehumidifiers or implementing active drying through airflow introduces an element of control, significantly cuts down on drying time, and proves to be a practical solution, especially when dealing with large-scale production. 

Drawing from my expertise, I can assert that making an informed choice on the drying method is paramount, as it directly influences your ability to achieve the optimal dryness for varied applications.

Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
Robert Johnson

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