100 Series Paddy-Brown Separator — How a Myanmar Commercial Rice Mill Recovered Head-Rice Yield with the 100 Series Paddy-Brown Separator

A commercial rice mill in Myanmar was losing head-rice yield without an obvious cause. The whitener settings were correct, the paddy moisture was within range, but broken rice percentages remained above target. The root problem was paddy carry-through from the husking stage — unhusked paddy grains passing into the whitener alongside brown rice. This case study examines how the Starlight 100 Series Gravity Paddy-Brown Separator resolved the separation gap and what operators should look for when carry-through is suspected.

Operation Background

A commercial rice milling operation in the Ayeyarwady Delta region of Myanmar — one of the country's most productive rice-growing areas — was running a mid-scale processing line at approximately 1,500 kg/h paddy input. The line processed primarily long-grain Indica varieties, with output directed to domestic commercial buyers specifying a head-rice yield minimum and a broken rice percentage cap.

The operation had been running for two years on a configuration that included a rubber-roll husker, a basic gravity separation table, a single-pass whitener, and a polisher. Performance during the first year was acceptable — head-rice yield was consistently at or slightly above the buyer's minimum, and broken rice percentage was within the contracted cap.

During the second year's main harvest season, performance dropped. Broken rice percentage crept above the contracted threshold repeatedly. The whitener settings had not changed, paddy moisture at intake was within the normal range, and the rubber rolls were replaced on schedule. The operations manager spent several weeks adjusting whitener pressure and feed rate without finding a setting that consistently met the contracted specification.

The Challenge

The problem was not at the whitening stage. It was upstream.

A rubber-roll husker operates by passing paddy grains between two counter-rotating rubber rolls under calibrated pressure. The pressure differential strips the husk from each grain. With ideal paddy flow and roll condition, husking efficiency typically runs at 85–90% per pass — meaning a proportion of grains passes through the husker without being husked.

In a correctly configured line, the paddy-brown separator captures this unhusked fraction and returns it to the husker for a second pass before any grain proceeds to the whitener. If the separator is not performing to specification — whether due to wear, miscalibration, or insufficient separation capacity for the throughput — unhusked paddy grains carry through into the whitener alongside brown rice.

This is mechanically significant. The whitener is calibrated for brown rice — grain with the bran layer intact, ready for milling. Paddy grains entering the whitener still carry their husk. The husk introduces an irregular hard surface that interacts with the whitening roll differently from bran. The result is inconsistent bran removal, elevated mechanical stress on individual grains, and — because the husk is harder than bran — increased breakage concentrated at the grain tips.

In the Myanmar operation, the existing gravity separation table was operating at approximately 1,400–1,500 kg/h — the upper limit of its rated capacity. As harvest-season paddy volumes pushed throughput toward that ceiling, separation efficiency degraded. Carry-through increased. Broken rice percentage rose.

Equipment Selected

100 Series Gravity Paddy-Brown Separator

The Starlight 100 Series Gravity Paddy-Brown Separator is available in configurations from 100×6 to 100×16, with separation capacity scaled to line throughput. For the Myanmar operation's 1,500 kg/h paddy input rate, a mid-range 100 Series configuration was selected — providing separation capacity above the line's current throughput ceiling with headroom for planned capacity expansion.

The 100 Series operates on gravity stratification: the mixed paddy-and-brown-rice stream from the husker is fed onto a series of reciprocating sieves with controlled airflow. Brown rice — denser and with a higher coefficient of friction on the sieve surface — stratifies and is discharged at one end. Lighter, smoother-husked paddy grains stratify separately and are discharged at the return-to-husker outlet.

Separation efficiency of the 100 Series at correctly calibrated settings consistently exceeds 95% per pass, meaning less than 5% of unhusked paddy proceeds to the whitener after a single separation cycle. For operations where carry-through has been identified as the source of elevated breakage, this represents a significant and measurable improvement over degraded or undercapacity separation.

Configuration and Deployment

The 100 Series Paddy-Brown Separator was installed in the existing position of the gravity separation table, with minor adjustments to the inlet and outlet chute heights to match the new unit's connection points. The paddy return line — directing unhusked grains back to the husker — was retained from the existing layout.

Airflow calibration was set to the brown rice bulk density for the operation's Indica variety. Reciprocation speed was adjusted during commissioning with the line running at normal throughput until the discharge streams were visually clean — brown rice at the whitener inlet with no visible unhusked grains, paddy at the return outlet with minimal brown rice carry-back.

Commissioning was completed in a single shift. The operation's maintenance team participated in the calibration process so they understood the adjustment parameters and could recalibrate independently if the paddy variety or throughput rate changed between seasons.

Results

Within the first week of operation with the 100 Series installed, the Myanmar mill's output quality returned to within specification. Broken rice percentage dropped back below the contracted threshold and remained there through the remainder of the harvest season.

The whitener settings that the operation's manager had spent weeks adjusting were returned to their original calibrated values. The inconsistency that had appeared to be a whitening problem resolved entirely once the paddy carry-through reaching the whitener was eliminated.

Head rice yield improved by approximately 1.5–2 percentage points compared to the underperforming period. On a line processing 1,500 kg/h, a 2-point improvement in head-rice yield is commercially significant — it represents the difference between meeting the buyer's specification and a penalty clause or batch rejection.

The operation's manager noted that the improvement in output consistency also simplified downstream quality checking. When paddy carry-through was intermittent, quality checks were required more frequently because output could shift during a shift. With consistent separation, quality checks returned to their normal frequency, and results were predictable between inspections.

Who This Machine Suits

The Starlight 100 Series Gravity Paddy-Brown Separator is the right solution for:

Commercial mills are experiencing elevated broken rice percentage, where whitener adjustment has not resolved the problem, and paddy carry-through from the husking stage has not been ruled out as the cause.

Operations running at or near the capacity ceiling of their existing separation equipment, where throughput has grown to the point where a one-size-fits-all separation table is no longer performing at the efficiency the line requires.

New production line builds from 1.0 to 3.0+ t/h, where paddy-brown separation is being specified from the outset and the configuration needs to match the husker throughput with separation efficiency and capacity headroom for future growth.

Multi-pass whitening lines where a second whitening pass is being used to compensate for paddy carry-through rather than the underlying separation stage being corrected — a configuration that increases energy consumption and mechanical stress without addressing the root cause.

For a full explanation of the rice milling processing sequence and how paddy-brown separation fits within it, see Rice Milling Process: Complete Guide.

Frequently Asked Questions

How do I know if paddy carry-through is affecting my output quality?

The most direct method is to sample the whitener inlet stream and manually inspect a small quantity of grain under good lighting. Unhusked paddy grains are visually distinct from brown rice — they retain the yellow or gold husk that brown rice has had removed. If more than 2–3% of grains at the whitener inlet are visibly unhusked, carry-through is occurring at a level that will affect output quality. Elevated broken rice percentage that does not respond to whitener adjustment is a common symptom.

What is the difference between the models in the 100 Series range (100×6 to 100×16)?

The numeric suffix refers to the number of separation decks in the unit. More decks provide higher throughput capacity and improved separation efficiency at higher feed rates. The correct model for a specific line is determined by the paddy input rate at the husker — not the husker's rated maximum, but the actual operating throughput the line runs at. Discuss your throughput with Starlight's engineering team to confirm the appropriate 100 Series configuration.

Can the 100 Series handle multiple grain varieties on the same line?

Yes, with recalibration between varieties. Brown rice bulk density varies between grain types — Japonica is denser and shorter than Indica, Basmati is longer and lighter. The separation calibration — airflow and reciprocation speed — should be adjusted when the paddy variety changes significantly. For operations that process multiple varieties in the same day, the recalibration takes approximately 15–20 minutes and should be done at the point the variety changes to maintain separation efficiency across the shift.

Discuss Your Paddy Separation Requirements with Starlight's Engineering Team

If paddy carry-through is suspected as a source of elevated breakage or inconsistent whitening output, Starlight's engineering team can review your line configuration and recommend the appropriate 100 Series specification for your throughput and grain profile.

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