Granular organic fertilizer plant
Granules sell at a premium because they can be spread by machine, stored without caking and packed attractively. The premium is earned by controlling
01
A medium plant, section by section
| Section | Duty | Configuration notes |
|---|---|---|
| Reception & dewatering | 60–250 t/day fresh material | Hardstanding reception, screw or inclined-screen separation where manure arrives as slurry |
| Mixing & amendment | Moisture and C/N correction | Batching scale or volumetric dosing; the accuracy here sets the consistency of everything downstream |
| Fermentation | 4–10 t/day of finished equivalent in process | Groove bays with a travelling turner, or aerated static piles with blowers and a plenum |
| Grinding | Cured material to < 3–5 mm | Semi-wet crusher or hammer mill with dust extraction; moisture above 20% blinds screens |
| Granulation | Formation of 2–4 mm granules | Disc, rotary drum or stirring-tooth granulator depending on feedstock plasticity and binder |
| Drying & cooling | Moisture to 12–14% | Rotary dryer with hot-air generator and a cooler; the largest thermal and electrical load in the plant |
| Screening & coating | Size classification and surface treatment | Second screening pass with recirculation, then coating drum for anti-caking and slow release |
| Bagging & palletising | 5–50 kg bags | Automatic weighing, stitching or sealing, check-weighing; palletising optional at this scale |
02
The drying decision
Adding a dryer is the change that turns a composting workshop into a fertilizer factory — and the change that most often disappoints. The dryer is sized on the inlet moisture you actually achieve after granulation, which depends on the moisture of the cured material and the water added as binder. If the cured material arrives at 30% instead of 20%, the dryer that was specified for 4 t/h will evaporate water, not produce product, and daily output falls far below nameplate.
The engineering answer is to control moisture before the dryer: keep the fermentation and curing discipline, use a binder that adds as little water as possible, and specify the dryer on the worst credible inlet moisture rather than the best. Plants that treat the dryer as the place where moisture problems are solved usually run at 50–70% of design output and burn far more fuel than budgeted.
03
Choosing the automation level
- Semi-automatic — operator places the bag, scale fills it, operator stitches. Robut and inexpensive; requires two operators per bagging station.
- Automatic bagging — automatic weighing, bag placing and sealing, with check-weighing and rejection. Reduces labour sharply and improves bag-weight consistency, which matters for retail compliance.
- Automatic palletising — robot or high-level palletiser with stretch wrapping. Justified at higher output or where bag weight exceeds 40 kg.
- Process control — temperature and moisture monitoring in fermentation, interlocks on the drying and grinding sections, and production records per batch. This is the automation that actually protects product quality.
04
Utility demand at 4–10 t/h
| Utility | Powder line | Granular line with drying |
|---|---|---|
| Connected load | 200–400 kW | 350–900 kW |
| Process water | 40–90 m³/day | 50–120 m³/day |
| Drying fuel | — | 600–2,000 kg/h of biomass, coal or gas equivalent depending on inlet moisture |
| Dust extraction | 20,000–40,000 m³/h | 40,000–90,000 m³/h |
| Odour extraction | by site constraint | 20,000–60,000 m³/h with biofilter or scrubber |
| Shift labour | 10–16 | 16–24 |
Indicative planning values. The real figures follow the mass and moisture balance, fuel calorific value and site climatic conditions.
05
Delivery and ramp-up
- 01
Months 1–2 — design
Design basis, process design, layout and civil drawings; civil works start on site.
- 02
Months 2–5 — fabrication
Equipment fabricated and pre-assembled in the works, with a factory check of the main sections.
- 03
Months 5–7 — delivery and erection
Shipping, clearance and erection, coordinated with the civil contractor's completion dates.
- 04
Months 7–8 — commissioning
Cold and hot commissioning at increasing load, trial batches, product testing and operator training.
- 05
Months 8–12 — ramp-up
Output typically reaches design rate over the first two to four months as fermentation stabilises and operators gain control of the line.
Size a medium plant
Give us the feedstock tonnage, the product form and the site area; we return a section-by-section configuration with utility demand.
FAQ
Plant engineering questions
Should a medium plant make powder or granules?
Granules usually earn more per tonne but require a dryer, more utilities and tighter process control. Many customers start with powder and add granulation in phase two on the same plot — the layout should reserve that space from the beginning.
What causes the biggest difference between design output and real output?
Inlet moisture to the dryer, and fermentation consistency. Both are process control issues rather than equipment issues, and both are visible in the first month of production records.
How much storage should the plant have?
Plan for two to four weeks of finished product under cover, plus enough cured-material buffer to keep the processing line running for a week when fermentation lags. Buffer volume protects the schedule far more cheaply than extra machine capacity.
Do you provide the laboratory equipment?
We specify the basic instruments — moisture meter or oven, granule strength tester, sieve set, pH and temperature probes — and can supply them. Nutrient analysis for labelling is normally done by a local accredited laboratory.
Send us your design basis
Tell us the feedstock, the daily tonnage and the product you want to sell. The engineering team replies with the plant configuration, the equipment scope and the information we still need before layout drawings start.
- Feedstock profile — type, moisture, contamination, seasonal peaks
- Capacity — t/day fresh material or t/h finished fertilizer
- Product — powder, granules, bagged retail, bulk compost
- Site — available area, power supply, water, access road
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