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Assessment of Production

Kernel Stone Contamination

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Introduction

High stone contamination resulted in PK deduction of 30MT &25MT on Sept

& Oct 2011 respectively.

Possible faulty of machineries were checked (damper, cyclone & airlock).

Silo Kernel quality was given hourly attention

Dampers were adjusted correspond to lab sample quality.

However, after silo kernel stone % still fluctuated between 0.18% - 5.04%. Due to the inconsistency of PK stone %, this survey is carried out.

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November 17th

The source of Small Stone was investigated.

Press Cake

Nut

Before Silo

Before Silo

6.35 gram

0.62% to

P.Cake

Press #4

17/11/2011

Press Cake

61.05 gram

5.41% to P.CakePress #4

17/11/2011

6.69 gram

0.60% to P.D. Nut

P. Drum

17/11/2011

Polishing Drum Nut

Polishing Drum Nut

28.18 gram

2.43% to P.D.

Nut

P. Drum

17/11/2011

12.64 gram

1.16%

Before Silo

17/11/2011

8.72 gram

0.73%Before Silo

17/11/2011

Press cake stone Avg. 2.73%, before silo stone high 1.16% &

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November 18thPress Cake

Press Cake

Press Cake

Polishing Drum Nut

Polishing Drum Nut

Polishing Drum Nut

Before Silo

Before Silo

Before Silo

2.85 gram

0.25% to P.Cake

Press #4

18/11/2011

4.03 gram

0.37% to P.Cake

Press #6

18/11/2011

19.47 gram

1.62% to P.Cake

Press #5

18/11/2011

69.66 gram

6.40% to P.D. Nut

P. Drum

18/11/2011

6.64 gram

0.60% to P.D. Nut

P. Drum

18/11/2011

5.74 gram

0.51% to P.D. Nut

P. Drum

18/11/2011

5.01 gram

0.45%

Before Silo

18/11/2011

17.53 gram

1.61%

Before Silo

18/11/2011

11.02 gram

1.00%

Before Silo

18/11/2011

Press cake stone Avg. 0.75%, before silo stone high 1.61% &

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smaller stones were carry forward from press cake to nut bin and finally to

kernel silo.

Press PolishingDrum

Destoner LTDS #1 Before Silo

Filtered stonesfrom press cake

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November 17thNovember 18th Cont.

Stones in PK were similar in size and weight if not larger comparing to

kernel. (Refer to Figure 1) This resulted in difficulty of air separation.

LTDS Kernel (Dry) & Hydro cyclone Kernel (Wet) were studied for stone %

and found that 100% stone contamination was contributed by LTDS kernel

(Dry).

Wet shell was sampled and found that the stone size in wet shell was

relatively small. (Refer to Figure 2) Reconfirmed hydro cyclone separation efficiency.

Kernel Stone

1.12 gram 1.72 gram

Figure 1

Wet Shell Mini Stones

Figure 2

0.03 0.14 gram

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November 20thNovember 25th

Production kernel with low stone % is stored in bunker #2 and blended with

bunker #1 for despatch.

Since air separation is not reliable to tackle our present problem, mill did a

trial to feed in more chipped mixtures to hydro cyclone for water separation

by adjusting LTDS #2 damper.

Ripple mill throughput was fixed for control convenience.

LTDS #1 damper reduced, LTDS #2 damper was opened more.

LTDS losses was monitored during the trial.

Average LTDS losses significantly higher than target, during the trial mill had

to sacrifice broken kernels to improve stone contamination.

Date

Kernel Losses Stone %

LTDS1 LTDS2 LTDS Avg.

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November 20thNovember 25th Cont.

Due to the nature of air separation, feed in to hydro cyclone via LTDS #2 is

not effective.

Before silo stone < 0.5% was not constantly achievable (refer to Table 1).

Therefore, workshop started fabricating new trunking to by-pass LTDS #2

(Line 1) chipped mixtures to hydro cyclone.

Airlock Airlock Airlock HydrocycloneChipped Conveyer

Wet Kernel

Boiler Dry Shell

Conveyer

1st Stage LTDS 2nd Stage LTDS

Previous Setup

R. Mill

Airlock Airlock Airlock HydrocycloneChipped Conveyer

Wet Kernel

Boiler Dry Shell

Conveyer

1st Stage LTDS 2nd Stage LTDS

Current Setup

R. Mill

Current setup using water separation entirely.

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November 24thNovember 25th

The new trunking was ready and put into testing. (Right Picture)

Necessary mechanical modifications were made. (Left Picture)

During the testing, LTDS damper and hydro cyclone were adjusted

according to PK quality by supervisors.

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Hydro Cyclone Fine Tuning Wet shell losses & dirt before silo were utilized as tuning parameters.

Mill running two hydro cyclone for tuning by trial & error. (Left Picture)

Shell was minimized on Stage 1 & 2, while kernel minimized on Stage 3

during tuning.

Stage 3

Stage 2

Stage 1

Stones

Wet Shell KernelLosses

Wet Shell Kernel Losses

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November 26th onward New trunking was put to use officially, data comparison as table below,

Date

Kernel Losses Stone %

LTDS1 LTDS2LTDS Avg.

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Future Problem Due to New Setup

# Pros & Cons Effect

1Carryover of hydro cyclone

water into kernel silos

Molding and odor of production kernels.

Longer kernel cooking time, risk of uncooked kernel.

2 Carryover of LTDS fiber toproduction kernel Molding and odor of production kernels due to watercarryover by LTDS fiber.

3

Wear and tear of

hydrocyclone mechanical

components (cone, impeller

etc.)

Increase maintenance cost & reduce hydrocyclone

efficiency

4 More wet shell excess

Wet shell Increased to average 1.25% from 0.65% per

tonne FFB. (converts to 10MT excess wet shell

processing 800 MT FFB)