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Groundnut oil processing
Groundnut cleaning, shelling, roasting, oil extraction and filtration — filtered groundnut oil, cold-pressed oil, groundnut cake
The commercial reality
Groundnut oil is an extraction business. A tonne of pods gives roughly 290 kg of filtered oil and 380 kg of protein-rich cake, so every kilo of oil left in the cake is margin left on the table. The sheller sets how many kernels you keep, conditioning sets how freely the oil runs and the expeller decides how much oil leaves the cake. Filtration then decides whether the oil sells as a premium bottle or a bulk drum.
Process flow diagram
Generated for the standard configuration. Yours is redrawn to your product mix, capacity and site.
Process chart
Every stage with the equipment that performs it, the operating parameter and the control point that decides quality.
| # | Stage | Equipment | Parameter | Control point |
|---|---|---|---|---|
| 01 | Cleaning | Pre-cleaner and destoner | Vibrating sieve, destoner, magnet, aspiration | Stones, metal, soil and stalks removed |
| 02 | Shelling | Groundnut decorticator | Rotor and grate, clearance set to pod size | Kernels shelled with minimum splits |
| 03 | Kernel separation | Aspirator and grader | Air aspiration, size grading, sorting | Shell out, mouldy and shrivelled kernels out |
| 04 | Roasting / conditioning | Roaster or steam kettle | Dry roast for flavour or steam condition, 100–110 °C | Moisture and temperature into the press |
| 05 | Crushing | Kernel cracker | Kernels cracked to uniform pieces | Even feed for the expeller |
| 06 | Expelling | Oil expeller | Single or double pass screw press | Residual oil in cake, 6–8% |
| 07 | Settling | Settling tank | Gravity settling of crude oil | Foots recycled to the expeller |
| 08 | Filtration | Plate and frame filter press | Plate and frame press with filter cloth | Clear oil, no suspended solids |
| 09 | Polishing | Polishing filter and tanks | Fine bag or cartridge filter into SS tanks | Clarity and shelf life |
| 10 | Filling | Oil filling and capping line | Volumetric or weigh filling, capping, labelling | Fill volume, seal and batch coding |
Mass balance
Basis of 1,000 kg of raw material. Change the tonnage below and the whole table rescales.
| Stage | Output, kg/h | Yield | Loss, kg/h | Where the loss goes |
|---|---|---|---|---|
| Groundnut pods received | 1,000 | 100% | 0 | — |
| After cleaning | 980 | 98% | 20 | Stones, soil, stalks and dust |
| Kernels after shelling | 700 | 70% | 280 | Shell, sold as boiler fuel or briquettes |
| Graded kernels | 690 | 69% | 10 | Mouldy, shrivelled and broken kernels removed |
| Conditioned kernels | 675 | 67.5% | 15 | Moisture driven off in roasting |
| Crude oil from expeller | 298 | 29.8% | 377 | Groundnut cake at 6–8% oil — the second product, not a loss |
| Filtered oil | 292 | 29.2% | 6 | Foots and filter sludge, returned to the expeller |
By-products: Groundnut cake (about 380 kg per tonne of pods) sold as high-protein animal feed or to a solvent plant; shell sold as boiler fuel or pressed into briquettes.
Equipment schedule
Core machines for this line. Conveying, oil tanks, pumps and utilities are added to suit the layout.
| Equipment | Category | Function |
|---|---|---|
| Pre-cleaner and destoner | Preparation | Removes stones, metal and field dirt that wear out the expeller. |
| Groundnut decorticator | Preparation | Shells pods; rotor clearance sets kernel splits and losses. |
| Aspirator and grader | Separation | Blows off shell and removes mouldy kernels — the main aflatoxin control. |
| Roaster or steam kettle | Thermal | Brings kernels to the right moisture and temperature so the oil runs freely. |
| Kernel cracker | Preparation | Breaks kernels into uniform pieces for steady expeller feed. |
| Oil expeller | Separation | Screw press that separates oil from cake; the yield machine of the line. |
| Settling tank | Separation | Lets foots settle out of crude oil before filtration. |
| Plate and frame filter press | Separation | Removes fine solids to give clear, bright oil. |
| Polishing filter and tanks | Separation | Final fine filtration and storage in stainless steel. |
| Oil filling and capping line | Packing | Fills bottles, jars and tins, then caps, codes and labels. |
Questions we get on this line
Cold-pressed or roasted and filtered oil?
Cold-pressed oil is pressed without roasting at low temperature; it keeps a light, natural flavour and sells at a premium, but yields less oil per tonne. Roasting or steam conditioning before pressing gives more oil and a stronger nutty aroma. Many plants run both and sell to different customers.
Expeller only, or expeller plus solvent extraction?
An expeller leaves about 6–8% oil in the cake. Solvent extraction can bring that close to 1%, but it is a separate, larger plant with its own safety and capital needs. Most mid-size mills sell the cake to a solvent plant or as feed instead of building one.
How do we keep aflatoxin out of the oil and cake?
Aflatoxin starts in the field and in storage when pods stay damp. Dry pods to a safe moisture before storing, keep the store dry and ventilated, and remove mouldy and shrivelled kernels at grading. Cake is where aflatoxin concentrates, so feed buyers will test it.
Want this line costed for your tonnage?
Send your groundnut variety, kernel oil content and the capacity you are targeting. You get a flow diagram, an equipment schedule and a budget number.