4 T/H Mixed Biomass Bedding Pellet Line in Croatia

RICHI MACHINERY

Project Overview

This mixed biomass bedding pellet line in Croatia was developed for a client already collecting agricultural residues and wood-processing by-products. The commercial problem was not a shortage of material. It was the low value, low bulk density and difficult handling of loose straw, especially outside the main harvest period. Converting part of that stream into bedding pellets created a product that could be stored, transported and dosed more easily by livestock farms.

The project was discussed from February 2025, entered detailed engineering in the first half of the year, and moved through manufacturing, shipment, installation and commissioning during the same project cycle. The plant is designed around wheat and corn straw with a smaller proportion of wood sawdust, producing 6–8 mm pellets for bedding rather than fuel.

The project is classified as a 4 T/H bedding pellet line and operates one 8-hour shift per day for 300 days. Four parallel MZLH420 pellet mills provide a combined installed pelleting window of about 4–5 T/H, allowing the plant to sustain the approximately 4.17 T/H average required to produce 10,000 tons of finished bedding pellets per year while retaining operating margin for raw-material variation.

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Why the Client Chose Bedding Pellets

The client did not begin with a conventional fuel-pellet business plan. The available biomass came from two directions: cereal straw collected from nearby farmland and sawdust generated by small wood workshops. Both were usable materials, but both were difficult to monetize consistently in loose form. Straw took up large storage volumes and its value changed sharply after harvest. Sawdust was easier to handle but came from multiple small suppliers rather than one industrial source.

Bedding offered a different route. Livestock farms already understand straw as a bedding material, so the project did not need to create a completely new end use. The processing objective was to reduce volume, improve handling, control loose dust and deliver a product that could be stored in bags or bulk form and broken down again after contact with moisture.

This distinction shaped the plant. Fuel-pellet projects normally focus heavily on calorific value, ash and combustion standards. Here, the more relevant operating questions are absorbency, fines, cleanliness, pellet integrity during transport, ease of breakdown in the barn and compatibility with manure-handling practices after use.

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Raw Material Plan

The project planning basis uses approximately 8,000 tons of wheat and corn straw and 2,000 tons of wood sawdust per year. These quantities describe the available annual feedstock pool rather than a guaranteed one-to-one finished-product balance. Some material remains outside the pellet route because of moisture, contamination, screening rejects or purchasing timing, while the final blend changes with bedding performance and material condition.

Straw is stored separately from sawdust so the operator can change the blend instead of accepting whatever ratio arrives at the plant that day. Bales or loose straw exposed to rain are isolated from the normal production queue. The line does not rely on a large thermal dryer, so incoming moisture has to be controlled through purchasing, covered storage and batch management.

Feedstock consistency is one of the main operating controls. Long straw is first opened and coarse-cut, then the hammer-mill stage reduces it to a practical 3–5 mm range before blending and pelleting. This sequence keeps long fibers away from dosing screws while avoiding excessive fine dust.

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Finished Bedding Pellet Specification

The finished product is a mixed-biomass bedding pellet rather than a fuel pellet. The plant produces 6–8 mm pellets because this size is practical for farm handling and gives the client flexibility to match different bedding-use preferences without changing the overall line concept.

The sawdust share is not fixed simply to maximize pellet hardness. Too much wood material can change how the bedding expands and absorbs liquid, while too little can reduce pellet integrity depending on the straw condition. During commissioning, the blend is adjusted around actual absorbency, fines and handling performance rather than a theoretical formula alone.

No routine binder addition is required in this process. However, successful binder-free operation still depends on moisture, fiber size, sawdust proportion, die compression and stable feeding.

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Capacity Plan and Annual Output

The normal schedule is one 8-hour shift per day for 300 days, or 2,400 planned production hours per year. The four MZLH420 pellet mills provide about 4–5 T/H of combined installed pelleting capacity. Producing 10,000 tons per year requires an average of about 4.17 T/H, which falls within that installed window while leaving limited operating reserve for variation in straw condition and routine stoppages.

The configuration is therefore sized around the completed project’s 10,000 T/Y duty rather than around a theoretical single-machine rating. Future output above this level would require a review of operating hours, grinding capacity, cooling, conveying and electrical supply before additional pelleting capacity is added.

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Equipment Configuration

The biomass pellet plant uses four MZLH420 ring-die pellet mills. Each unit has a 90 kW main motor and a biomass capacity of roughly 1.0–1.2 T/H, giving the pelleting section a combined installed window of about 4–5 T/H. This matches the completed project’s 10,000 T/Y output target and gives the operators room to balance straw proportion, bulk density and moisture variation.

Electrical control is organized as one coordinated plant system with local cabinets at the main process sections. This allows the four pellet mills, feeders, dust extraction, cooling and conveying equipment to be interlocked instead of operating as isolated machines.

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Process Flow for Straw and Sawdust Bedding Pellets

The line is simple compared with a wet-biomass fuel plant, but it still needs more than crushing and pelleting. The two raw materials behave differently, and the finished product must leave the line cool and screened if it is going directly into storage.

1. Receiving and segregation: straw and sawdust are unloaded into separate zones. Wet, contaminated or unsuitable material is held outside the normal production stream.
2. Bale opening and coarse straw cutting: long wheat and corn straw is opened and shortened before it reaches the fine-grinding machines.
3. Fine grinding: prepared straw and sawdust are reduced to approximately 3–5 mm. This is fine enough for stable ring-die feeding without turning the entire raw-material stream into unnecessary dust.
4. Buffering and blending: ground straw and sawdust enter separate bins and are metered according to the required bedding performance. Operators adjust the ratio when raw-material moisture or straw condition changes.
5. Pelleting: the prepared blend is compressed through the parallel biomass pellet mill system to produce 6–8 mm bedding pellets.
6. Cooling: hot pellets leave the die and enter a counterflow cooler sized for the full line so product temperature is reduced before screening and storage.
7. Screening: loose fines are separated after cooling. Suitable fines can be returned to the process instead of entering finished-product bags.
8. Packaging and storage: stable pellets move to the finished-product area for bagging or bulk-bag handling before delivery to farm customers.

Material bridging appeared during commissioning when wetter or longer straw reached the buffer bins. Hopper geometry, vibration support, screw-feeder speed and upstream cutting were adjusted together so the mechanical cause of bridging was addressed without disturbing the dust-extraction airflow.

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Electricity and Water Requirements

The completed line has an installed electrical load of about 500 kW. Four 90 kW pellet mills account for 360 kW, with the remaining demand coming from straw preparation, grinding, fans, conveying, cooling, screening and packaging equipment.

At the one-shift operating schedule, annual electricity consumption is approximately 930,000 kWh. The actual monthly total changes with straw condition, grinder loading and how many pellet mills are running simultaneously, but the site electrical system is sized for the full connected load rather than the average meter reading.

Because there is no large thermal dryer, the line does not require a major process-water or fuel system. This keeps utilities simpler, but the electrical connection still needs to be sized for simultaneous motor operation and starting current.

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Storage and Workshop Planning

The plant uses an existing workshop and organizes storage around turnover rather than annual stockpiling. Up to about 1,000 tons of straw and 200 tons of sawdust can be held at one time, with baled straw requiring the larger covered zone because of its low bulk density.

• Straw storage needs covered floor space, fire separation and enough aisle width for bale handling.
• Sawdust should be stored in a contained zone so fine material does not migrate into finished-product areas.
• Grinding and dust-collection equipment should be kept away from bag storage and routine forklift traffic.
• The four pellet mills need maintenance clearances on both die and drive sides rather than being packed tightly simply to save floor area.
• Finished bedding pellets should remain dry because moisture uptake before sale reduces storage stability and changes expansion behavior.

For a project of this scale, warehouse design can become more important than the footprint of the machines themselves. A buyer comparing quotations should therefore provide bale dimensions, delivery frequency and maximum stock days rather than only the production-line capacity.

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Dust Control and Operating Safety

Mixed straw and sawdust processing creates combustible dust at the same time that the plant handles a large volume of dry fibrous material. Six main extraction points with matched induced-draft fans are integrated into the plant dust-control system so the crushing, transfer and pelleting areas can be controlled together.

• Local extraction at crushers, transfer points and pellet-mill feeding areas.
• Enclosed conveying for fine ground material where practical.
• Magnetic protection before grinding and pelleting equipment.
• Routine removal of dust from motors, electrical cabinets, beams and cable trays.
• Fire separation between straw storage, production and finished-product storage.
• Controlled hot-work procedures for welding or maintenance inside the plant.
• Accessible emergency routes around bale stacks and equipment rows.

Because the product is bedding rather than food or feed, the plant does not need feed-hygiene controls. It still needs disciplined contamination control, particularly to keep treated wood, metal, stones, oil-contaminated sawdust or other unsuitable materials out of the bedding stream.

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Staffing and Daily Operation

The plant operates with 10 employees on the normal one-shift schedule. Production staffing covers raw-material receiving, bale handling, line supervision, packaging, warehouse movement and maintenance, while administration and basic quality control are handled by the remaining personnel.

The operator’s most important daily checks are not complicated laboratory tests. Moisture, fiber condition, hopper flow, pellet fines, bag weight, bearing temperature and die load give a much faster picture of whether the line is running normally. Bedding quality also needs a simple absorbency check because a pellet can look mechanically strong and still perform poorly in a barn.

This is especially important when straw comes from different farms. A line with four pellet mills can still lose output if one wet batch bridges in a bin or if long fibers reach the dosing screws. Production discipline upstream protects more capacity than pushing the pellet mills harder.

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Project Timeline

The project moved from the first technical discussion to on-site commissioning within the 2025 construction cycle because the client reused an existing workshop and did not need a large drying or furnace section.

1. February 2025: initial inquiry and discussion of available straw, sawdust and possible bedding applications.
2. March 2025: site survey and preliminary workshop layout planning.
3. April 2025: process route confirmed around bedding pellets rather than fuel pellets.
4. June 2025: contract signed and production planning finalized.
5. August 2025: equipment manufacturing completed and shipment arranged from Qingdao Port.
6. September 2025: site installation, dry commissioning and material trials carried out in Croatia.

The short schedule depends on having the building and core utilities available before equipment arrival. A greenfield project requiring a new workshop, transformer installation, major fire-water works or additional permitting would need a longer implementation period even with the same 4 T/H process capacity.

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Shipping and Local Logistics

The main equipment was shipped from Qingdao Port in August 2025 and then transferred to the Croatian project site through the client’s appointed logistics route. Container loading was organized by process section so installation could proceed in sequence after arrival.

This is also why freight should remain separate from machinery comparison. Two 4 T/H projects can have similar equipment lists but very different delivered costs if one site requires extra containers, long inland transport, special lifting equipment or temporary storage before installation.

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Investment Scope

The completed project’s fixed investment was approximately US$660,000. Because the client reused an existing workshop, the budget was concentrated on process equipment, electrical and control work, dust and safety upgrades, local foundations, freight, installation and commissioning rather than on construction of a new factory shell.

This investment level is consistent with a completed 4 T/H-class bedding pellet project in Croatia that reuses an existing workshop but installs four ring-die pellet mills, two grinding routes, coordinated dust control, cooling, screening, packaging and a plant-wide electrical system.

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What Commissioning Changed

The most useful lesson from commissioning was that raw-material handling controlled production stability more than nominal pellet-mill power. Batches of wetter straw were more likely to bridge in feed bins, while very dry material produced more fines. These problems could not be solved by one universal machine setting.

• Hopper angles and agitation were adjusted to improve fibrous-material discharge.
• Feeder speeds were tuned so the four pellet mills received a stable rather than surging load.
• Straw cutting and hammer-mill screens were checked when long fibers reached the dosing section.
• The sawdust ratio was adjusted when pellets became either too hard or too weak for the intended bedding behavior.
• Moisture checks were placed upstream in the receiving process so unsuitable batches did not reach the pellet section.

These are small changes compared with replacing major equipment, but they are the type of adjustments that determine whether a bedding line can hold production every day. The commissioning target is therefore not only to make a pellet. It is to find an operating window that can absorb reasonable variation in straw and sawdust without constant stoppages.

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RICHI Scope for the Croatia Project

RICHI’s role covered the production route from fibrous raw-material preparation through finished bedding-pellet handling. The engineering work focused on making several parallel machines operate as one line instead of simply supplying four independent pellet mills.

• Raw-material evaluation for wheat straw, corn straw and wood sawdust.
• Process design covering bale opening, coarse cutting, fine grinding, dosing, pelleting, cooling and screening.
• Equipment manufacturing and electrical coordination for the parallel pellet-mill arrangement.
• Dust-collection planning at the main crushing and transfer points.
• Layout planning around raw-material storage and maintenance access.
• On-site installation guidance and commissioning support.
• Operator training for feed adjustment, moisture checks, die/roller maintenance and startup/shutdown procedures.
• Expansion review if the customer later adds shifts or increases annual output.

The biomass pellet production line is therefore treated as a complete handling system. Bedding quality depends on every stage before and after the pellet press, not only on the rated output of the four ring-die machines.

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Planning a Biomass Bedding Pellet Project?

This Croatia case is most relevant to buyers who already have access to straw, sawdust or similar clean fibrous biomass and want to move beyond loose-material sales. The project does not depend on a complicated process, but it does depend on realistic preparation, storage and capacity planning.

Before selecting equipment, RICHI needs to know whether the straw is loose or baled, the bale dimensions, seasonal moisture range, sawdust particle size, desired bedding pellet diameter, annual operating hours, packaging format and maximum raw-material stock. Those details determine the real line configuration more accurately than a capacity number alone.

For a new biomass pellet project, send us your raw-material photos, moisture data, target output and workshop information. We can then determine whether the project needs drying, how the straw should be opened and ground, how many pellet mills are appropriate, and what utility capacity the site must provide.