Biomass Briquette Raw Material Dryer in Zambia

Why Zambia Was a Suitable Location for This Biomass Project

Zambia has a large agricultural sector in which maize is an important crop. Maize cobs and stalks are generated during harvesting and grain processing, while sawdust is produced by timber cutting and woodworking activities. These materials are not automatically suitable for every fuel process, but properly selected and prepared residues can be considered for biomass briquette production.

Research on Zambia's bioenergy potential has examined crop and forestry residues as possible resources for densified fuels. Maize residues are particularly relevant because maize accounts for a substantial share of the country's crop-residue energy potential. This provides a realistic basis for a project that combines agricultural residues with a smaller supply of wood-processing waste.

The customer in this case was a small-to-medium-sized biomass fuel processor serving local commercial users. Its raw materials were obtained from farms, grain-handling activities and woodworking operations within its procurement area. The business wanted to make better use of these materials by converting them into compact briquettes that would be easier to store, handle and transport than loose agricultural residues.

The key issue was not a lack of raw material. It was the inconsistent condition of that material when it arrived at the plant. Some maize cobs had been stored under cover after harvest, while other batches had been exposed to rain or ground moisture. Sawdust also varied depending on its source and storage conditions. A dedicated biomass briquette raw material dryer offered a way to manage these differences before briquetting.

The Selected Equipment: φ1.5 × 15m Rotary Drum Dryer

The selected machine was a single-cylinder rotary drum dryer with a diameter of 1.5 m and a length of 15 m. It was planned as an additional raw-material preparation unit within an existing briquette production operation.

This configuration was selected for the project's intended role, not on the assumption that drum dimensions alone determine throughput. The actual drying capacity depends on the incoming moisture, the target outlet moisture, the mixture's particle characteristics, the heat source and the required water evaporation rate. These factors must be checked before a guaranteed hourly capacity can be specified.

The listed temperature values are the supplied equipment reference parameters, not a universal operating recipe for maize cobs and sawdust. The actual operating temperature must be established according to the material's moisture, particle size, heat source and required final condition. The temperature of the biomass itself is not the same as the hot-air inlet temperature.

Raw-Material Mix: Maize Cobs Supported by Sawdust

The planned feedstock consisted primarily of crushed maize cobs, supplemented by sawdust from local wood-processing activities. Maize cobs were selected as the main agricultural residue because they can be collected after grain removal and prepared for densification. Sawdust provided a second biomass component that could be blended with the agricultural material when its properties and availability suited the intended briquette product.

For preliminary project planning, the customer considered a blend of approximately 70% crushed maize cobs and 30% sawdust by dry mass. This is an illustrative design assumption, not a verified customer formula or a universal recommendation. The final ratio would depend on the actual raw materials, moisture content, particle-size distribution, briquette press and required product strength.

The two materials require different preparation. Maize cobs generally need crushing to reduce them to a size suitable for mixing and compression. Sawdust may already be fine enough for the briquette press, although screening can be useful when it contains oversized wood pieces or foreign matter. Both materials should be checked for stones, metal and other contaminants before entering the production process.

Moisture is another important difference. Maize cobs stored under dry conditions may require little drying, while recently collected or rain-exposed material may contain substantially more water. Sawdust from different workshops can also vary. The dryer should therefore be operated according to measured feed conditions rather than assuming that every batch needs the same residence time.

The raw-material blend is prepared for fuel briquettes, not for animal feed or fertilizer. The material must be selected and processed with its intended combustion use in mind. Coatings, treated wood, plastic contamination and other unsuitable materials should be excluded from the fuel stream.

Why the Customer Added a Dryer Instead of Replacing the Briquette Line

The customer already had the principal equipment needed to prepare and compress biomass. Its immediate need was a more controlled drying stage between raw-material preparation and briquetting. Replacing the entire line would have introduced additional capital requirements without directly addressing the moisture variation that the operator wanted to manage.

A separate rotary dryer allowed the customer to retain the existing crusher, mixer and briquette press while improving one specific part of the process. It also made it possible to schedule drying around the condition of the incoming material. Batches that were already sufficiently dry could be handled differently from wetter loads, subject to the agreed operating procedure.

For a biomass processor relying on seasonal agricultural residues, this flexibility is useful. Maize-cob availability can increase after harvest, while sawdust supply may follow the production schedules of local woodworking businesses. The materials do not necessarily arrive at the same time or with the same moisture level.

The dryer was therefore intended to serve as a buffer between variable raw-material supply and the more controlled conditions required by the briquette press. Its purpose was to help prepare the mixture for compression, not to replace the machinery that forms the finished briquettes.

How the Biomass Briquette Raw Material Dryer Works

After crushing and preliminary screening, the prepared material is conveyed into the rotary drum. As the drum rotates, internal lifting elements redistribute the biomass, exposing it to the hot drying medium while the material progresses toward the discharge end.

Moisture evaporates as heat transfers to the wet particles. The exhaust stream carries away water vapor, while the material gradually moves through the drum. The final result depends on the incoming moisture, particle size, feed rate, airflow, drum speed and residence time.

For a mixture of maize-cob particles and sawdust, consistent feeding is particularly important. Very fine sawdust and larger cob particles may not behave identically in the dryer. The preparation system should produce a reasonably consistent feed, and the operating settings should be established using the actual blend rather than relying solely on a nominal recipe.

At the discharge end, the dried material can be transferred to a holding bin or the next stage of the existing process. Depending on the plant layout, the next step may include additional screening, blending or direct feeding to the briquette press. The material should be checked before compression to confirm that its moisture condition is appropriate.

A rotary drum dryer does not produce finished briquettes by itself. It prepares the raw material for densification. The briquette press remains responsible for forming the product, while cooling, screening and packaging equipment may be used downstream according to the customer's product and handling requirements.

Moisture Control and Briquette Quality

Moisture management affects how biomass behaves during compression. Material that is too wet may produce briquettes that are difficult to handle or require additional drying after forming. Material that is excessively dry may also affect the compaction behavior, depending on the feedstock and press design.

The aim is not simply to remove as much water as possible. The appropriate outlet moisture must be established through raw-material testing and briquette trials. The required condition can differ between maize-cob material, sawdust and their blends, so a single target should not be assumed to suit every batch.

The supplied dryer specification lists an inlet air temperature of 400–500°C and an outlet air temperature of 70–80°C. These are reference process values. They do not mean that the biomass should reach 400–500°C. The actual product temperature depends on moisture evaporation, heat transfer, residence time and operating conditions.

For this project, the customer would need to record incoming and outgoing moisture, feed rate and operating conditions. Briquette samples could then be evaluated for strength, durability, density and combustion-related requirements relevant to the intended market. These tests would help establish the appropriate combination of feedstock preparation, moisture control and pressing conditions.

Where the Briquettes Could Be Used

The finished product was intended as a solid biomass fuel for suitable commercial and institutional users. Depending on briquette dimensions, combustion equipment and local customer requirements, potential users may include businesses using compatible biomass-fired heating systems and other facilities that can handle densified agricultural residues.

Briquettes made from maize cobs and sawdust should not automatically be treated as a direct replacement for every type of charcoal, coal or firewood. Their practical use depends on heating value, ash content, moisture, combustion behavior and compatibility with the user's stove or boiler.

The customer therefore needed to establish a clear product specification before expanding its market. Consistent dimensions, adequate mechanical strength and suitable moisture are important for storage, transport and feeding into the end user's combustion equipment.

By preparing the raw materials more consistently before compression, the drying stage could help the customer work toward a more repeatable briquette product. The actual quality improvement would need to be demonstrated through production trials and finished-product testing.

Other Materials That May Be Suitable for Rotary Drying

Rotary drum dryers are used in a variety of biomass and industrial processes. Their suitability depends on the material's moisture, particle size, heat sensitivity, abrasiveness and intended application. The same dryer should not be assumed to handle every material without an engineering assessment.

• Wood chips and selected forestry residues can be dried before grinding, briquetting or other biomass fuel preparation when the dryer is sized for their moisture load.
• Other agricultural residues, such as suitable crop stalks and husks, may be dried before densification if their physical characteristics and intended fuel use are compatible with the system.
• Some plant-based industrial residues can be dried before further processing, provided the feed system and operating conditions are appropriate for the material.
• Selected wet industrial solids and mineral materials may also use rotary drying technology, but their abrasive, corrosive or heat-sensitive properties require separate evaluation.

These are potential applications of rotary drying technology, not a claim that the selected φ1.5 × 15 m machine can process every material without modification. A change of raw material may require a new assessment of feeding, heat supply, exhaust treatment, residence time and product quality requirements.

RICHI's Engineering Preparation Before Shipment

Before confirming the equipment arrangement, RICHI's technical team would need information about the customer's raw-material mixture, inlet moisture range, required outlet condition and expected feed rate. The particle sizes of crushed maize cobs and sawdust would also be relevant because they influence material flow and drying behavior.

The engineering review would cover the installation area, foundation requirements, feed and discharge interfaces, heat-source arrangement and exhaust handling. Dust collection and fire prevention are particularly important when processing dry biomass particles. The final safety measures must be matched to the plant layout, heat source and applicable local requirements.

RICHI Machinery could provide equipment drawings, installation dimensions, operating documentation and guidance for integrating the dryer with the existing crushing and briquetting equipment. The objective would be to prepare the site and interfaces before the machine arrived, reducing uncertainty during installation.

Commissioning would focus on stable feeding, moisture reduction and the condition of the dried blend. Operators would need guidance on routine inspection, lubrication, safe start-up and shutdown, and monitoring for abnormal operating conditions. Actual operating settings would be established using the customer's materials rather than relying on generic assumptions.

Shipping to Zambia Through the Port of Dar es Salaam

The proposed rotary dryer would be shipped by sea from Qingdao Port in China to the Port of Dar es Salaam in Tanzania. Dar es Salaam is an important maritime gateway for Zambia and other land-linked countries in the region.

Before shipment, the customer would need to confirm the installation dimensions, foundation preparation, access for maintenance and connections for feeding, discharge and the heat source. The exhaust and dust-control arrangement should also be coordinated with the site layout.

RICHI's drawings and technical documentation would support site preparation and the integration of the new dryer with the customer's existing equipment. The final shipping and cargo arrangements would be confirmed through the freight forwarder according to the actual order and transport plan.

Customer Feedback and Practical Evaluation

For a biomass briquette producer, the main question is whether the new dryer helps deliver material in a condition that the briquette press can handle consistently. In this project scenario, the key evaluation points were moisture variation between incoming batches, stability of the feed into the drum and the condition of the dried mixture at discharge.

The customer would also need to keep records of feed moisture, outlet moisture, feed rate and operating conditions. Briquette samples should be checked after production to see whether the raw-material preparation settings are suitable for the intended fuel product.

No direct customer quotation or verified commissioning results are included because actual project feedback has not been supplied. Before publishing this as a confirmed customer case, the purchase information, measured operating results and any testimonial should be checked against the real project records.

A Dedicated Drying Stage for Biomass Briquette Production

The biomass briquette raw material dryer in Zambia was selected to solve a specific processing requirement: reducing moisture in crushed maize cobs and sawdust before briquetting. The customer already had equipment for size reduction, blending and compression, so the new rotary dryer could be added as a focused upgrade rather than a complete production-line replacement.

The selected φ1.5 × 15 m dryer provides a defined configuration, with a reference drum speed of 3–12 rpm and the supplied hot-air temperature ranges. Its actual throughput and outlet moisture must be determined from the raw-material condition, evaporation load, heat source and downstream briquette requirements.

For businesses comparing a biomass briquette raw material dryer, biomass rotary dryer or agricultural residue dryer, the most useful information to prepare includes the feedstock types, their proportions, inlet moisture, particle sizes, required outlet moisture and expected hourly feed rate. These details allow RICHI Machinery to assess the drying duty and recommend equipment suited to the real production process.

The objective is to make better use of available biomass residues, prepare them more consistently for compression and help the customer integrate moisture control into its existing operation. A properly matched dryer should be selected around the actual material and production target, rather than drum dimensions alone.