Cottonseed hot press: 110-130°C cook + 80-110°C press, dark crude → NBD refining
Cottonseed hard data: whole-seed oil 18-22%, kernel oil 35-45%, hull 35-45% of seed, linters 5-15%, gossypol 0.4-1.7% (toxic, removed by heat + NBD refining). Hot-press flow: clean → delint (linter saw / acid) → dehull (sheller + aspirator) → cook 110-130°C × 30-60 min (moisture 8-12% → 6-8%) → grind/stir → hydraulic press 200-325 ton at 80-110°C, 100 kg/barrel, 30-45 min cycle → crude oil yield 14-18% whole seed / 28-35% kernel, residual cake oil 6-9% → settle 24 h → refining (degum + neutralize + bleach + deodorize) reduces free gossypol from ~0.04% to <0.045% per FAO/WHO standard.
Cooking spec
Steam-jacketed cooker 110-130°C × 30-60 min, moisture 8-12% → 6-8%, gossypol pigment glands ruptured. Below 110°C: under-cook → low yield. Above 130°C: protein scorching, darker oil.
Grinding and stirring
Roll mill or hammer mill → uniform particle size 1-3 mm → stirring tank for homogeneous moisture/temperature distribution before barrel loading. Prevents pressure pockets in 30-45 min cycle.
Hydraulic press parameters
200-325 ton press, 100 kg/barrel (kernel + hull as feed), cycle 30-45 min at 80-110°C jacket. Yield 14-18% on whole seed, 28-35% on kernel-only feed, residual cake oil 6-9%.
Cottonseed hot pressing process flow
Delinting → dehulling → cooking 110-130°C × 30-60 min → grinding/stirring → 200-325 ton hydraulic press at 80-110°C, 100 kg/barrel, 30-45 min cycle.
Hot-press sequence
Six-step hot-press flow with parameters
Clean + delint + dehull
Vibrating screen + magnetic separator → linter saw (mechanical) or acid delinter (chemical) → sheller + aspirator (hull 35-45% removed). Output: kernel-rich feed for higher yield.
Cook 110-130°C × 30-60 min
Steam-jacketed cooker, moisture in 8-12% → out 6-8%. Cell membranes rupture, gossypol pigment glands break (improves later refining gossypol reduction).
Grind + stir
Roll mill or hammer mill → 1-3 mm particles → stirring tank ensures uniform moisture/temperature before barrel loading. Critical for batch-cycle uniformity.
Hot press 80-110°C
200-325 ton hydraulic, 100 kg/barrel, 30-45 min cycle. Crude oil dark red/brown (gossypol + chlorophyll pigments). Cake discharged hot, cooled, bagged.
Post-press chain
Crude oil and cake handling
- Crude oil: dark red/brown, FFA 1-3%, gossypol ~0.04% free + 0.5-1.5% bound. Settle 24-48 h in jacketed tank → 200-300 mesh plate-frame filter → buffer tank → refining feed.
- Refining (NBD): degum (phosphoric acid 0.05-0.1%) → neutralize (caustic soda) → bleach (activated clay 1-2%) → deodorize (240-260°C × 30-60 min vacuum). Reduces free gossypol to <0.045% per FAO/WHO.
- Cake: 6-9% residual oil + 23-35% protein (with hulls) or 41-44% (decorticated meal). Hot cake discharge → cooler → 25/50 kg bagger or bulk silo for ruminant feed (gossypol-tolerant).
- Hulls: ruminant feed (high fiber), boiler fuel, or particle board feedstock. Hull handling area 50-100 m² for 10-30 t/d line.
- Capex by scale: 10-30 t/d gin-side $80-150k Phase 1; 50-100 t/d mill $300-600k including refining; pilot 1-3 t/d $30-60k.
Questions to confirm next
Why must cottonseed be hot pressed, not cold?
What gossypol limit applies to refined cottonseed oil?
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