American Water Chemicals, Inc. 9203 King Palm Dr. Suite A, Tampa FL 33619

Tel: 1-813-621-3932 Fax: 1-813-621-4085 WWW.MEMBRANECHEMICALS.COM

Membrane Autopsy Report

Date Nov/19/2008

Tests performed for Minera Yanacocha

Tests Performed by Di Yu

2

Table of Content Table of Content................................................................................................................ 2 Introduction....................................................................................................................... 3

Membrane information ................................................................................................... 3 Membranes autopsy tracking information .................................................................. 3 Background information ............................................................................................. 3

Procedure of autopsy....................................................................................................... 5 Shipping and Package: ..................................................................................................... 6 External inspection ........................................................................................................... 7

Fiberglass wrap ............................................................................................................... 7 Brine Seal and Anti Telescoping Device (ATD) ............................................................ 8

Weight Test...................................................................................................................... 10 ATD and Fiberglass Removal........................................................................................ 11 Membrane Sleeves and Spacer Inspection ................................................................... 12 Dye Test ........................................................................................................................... 13 Fujiwara Test .................................................................................................................. 14 Foulant and Scalant Collection...................................................................................... 15 Advanced foulant/scalant analysis ................................................................................ 16

SEM imaging and EDS analysis ................................................................................... 16 FTIR analysis ................................................................................................................ 19

Results Discussion ........................................................................................................... 20 Findings and discussion ................................................................................................ 20 Conclusion and recommendation.................................................................................. 20

Release of Liability.......................................................................................................... 21 Attachment ...................................................................................................................... 22

3

Introduction A membrane that was severely scaled during operation was submitted for autopsy analysis.

Membrane information

Membranes autopsy tracking information Element manufacturer: HW Process Technologies, Inc. Model: HWATFE 8040 SN: 8008519 Client and client address: Minera Yanacocha SRL, Lima Peru. Client Contact Person: Gustavo Escobar Client Contact Phone Number: +51-1-215-2600 Client Contact E-mail: Gustavo.escobar@newmont.com Date Autopsy Initiated: Nov. 19th 2008 Date Shipped: Nov. 7th 2008 Date Received: Nov. 14th 2008 Carrier: Senores International Millenium Cargo AWC Lab Reference Number: 20081119MA Autopsy performer: Di Yu

Background information 1. Describe the feed water source for the RO Unit in question?

See AWC water chemistry projection attachment.

2. List the equipment in the Pretreatment System in the order they appear in the process. Make the description as specific as possible. Provide chemical manufacture and dosage level if possible. Merrill Crowe plant press filter barren tank Antiscalant dosing Nalco 9714 Bag filter hp pump for RO membrane system.

4

3. Describe the configuration of the RO system:

1st Stage 2nd Stage 3rd Stage Array, number of pressure vessel 36 24 12

Pressure drops (PSI) -13 6 -2

Elements per pressure vessel 6 6 6

Types of membrane elements in each vessel and stage

HWATFE 8040 HWATFE 8040 HWATFE 8040

Insert a chart of the RO system configuration if necessary. 4. Describe the position of the membrane element sent for autopsy:

RO Skid: Stage: Position:

5. Describe the problem of the membrane (pressure build up, performance degrading, reduced production, increased maintenance cost, etc.): Pressure build up and reduced production.

5

Procedure of autopsy Based on the pre-diagnosis, certain autopsy tests will be determined to be performed at the AWC Laboratory. This section contains a brief description of the tests; the ones to be performed on this specific autopsy report are marked with . Photographs are taken throughout the autopsy to record the progress. Any sign of abnormal condition of the membrane element will be reported on this document.

1. Examination of the shipping container for damage incurred during shipment. 2. Examination of the external construction of the element, including the

fiberglass shell, ATDs, and brine seal, for damage incurred during operation and/or shipping.

3. Weight measurement and bubble test to estimate scale problem and integrity. 4. Examination of the feed and concentrate ends of the element before and after

removal of the ATDs. 5. Removal of the fiberglass shell. 6. Examination of each individual membrane sheet for evidence of channeling,

fouling, and/or manufacturer defects. 7. Examination of glue lines. 8. Measurements of active membrane area, for comparison against the

manufacturers specifications. 9. Testing of three membrane samples with flat sheet testing setup, representing

the feed, middle, and concentrate portions of the element, for determination of membrane damage.

10. Perform dye testing to verify the integrity of the membrane sample 11. Perform Fugiwara tests for membrane samples to identify chlorine damage if

such damage is suspected. 12. Perform SEM, EDS and FTIR analysis for samples of the membrane sheet if

ordered by customer. 13. Collect and extract foulant and/or scalant found on the membrane surface. 14. Perform at least but not limited to, acid test, SEM, EDS, XRD and FTIR

analysis for the foulant and/or scalant. 15. Perform BART (Biological Activity Reaction Test) for the foulant materials to

determine presents of bio-fouling..

6

Shipping and Package: Description of the shipping and package condition: Delivery date and time: Nov. 14th afternoon Package materials: paper box Packaging Description: Box was broken and membrane was exposed. Sealing: A plastic cover wrapped the membrane. Part of the plastic cover was broken. Is the membrane wet or dry? : Half dry Additional observations (appearance, damage observed, etc):

Membrane package was broken as delivered.

Membrane was wrapped with a plastic cover.

7

External inspection

Fiberglass wrap 1. Manufacturer, Model and SN:

Element manufacturer: HW Process Technologies, Inc. Model: HWATFE 8040 SN: 8008519

2. Gel coat (crack or deformation observation): Gel coat cracked on feed side.

3. Finish (Fiberglass manufacture quality) Fiberglass surface is covered with scale.

4. Additional note (attach photos if available)

Fiberglass close to feed side cracked Fiberglass close to concentrate side cracked

8

Membrane fiberglass was partially covered with scale.

Brine Seal and Anti Telescoping Device (ATD) 1. Brine Seal condition (sign of degradation and leakage):

Brine seal is dirty with badly scaled surface.

2. Upstream ATD (integrity and make) Upstream feed side ATD cracked. The element sleeves formed telescope from the feed side.

3. Downstream ATD (integrity and make) Dent in two places and cracked in one area.

4. Odor and touch Light smell, dry to touch.

5. Additional notes (attach photos if available)

9

Crack on feed side ATD Crack on concentrate side ATD

10

Weight Test 1. Testing condition Dry/Wet:

Half dry

2. Testing results in Pound or Kg 85 lbs or 38.5 Kg

3. Additional notes (attach photo if available) Clean membrane should have a weight of approximately 35 lbs or 19.5 Kg.

11

ATD and Fiberglass Removal 1. Remove upstream and downstream ATDs.

See attached photo.

2. Inspect the feed side and concentrate end of the element. Heavily scaled and telescoping is visible.

3. Remove fiberglass wrap. See attached photo.

4. Additional notes. (attach photo if available)

Feed side ATD removal Concentrate side ATD removal

Fiberglass was partially removed

12

Membrane Sleeves and Spacer Inspection 1. Number of sleeves and spacers

20 sleeves and 20 spacers

2. Condition of the sleeves Severely scaled

3. Condition of the spacers Severely scaled

4. Active membrane area and glue line (check the glue line condition and measure the glue line width, estimate active membrane area)

The glue line is not uniform.

5. Additional notes (smell, touch, foulant, scale, attach photo if available)

Severely scaled membrane surface Severely scaled spacer

Scale collection from spacer Uneven membrane sleeve glue line

13

Dye Test Three sections of membrane were cut from the feed end, middle and concentrate end of the element. Each was tested with a dye solution to determine if the membrane had been damaged. A blue green dye solution is applied to the feed side of the membrane sheet. If the membrane is damaged, dye color can be observed from the permeate side of the membrane. Photos of the dye at feed side and permeate side are provided for comparison.

The dye was applied to the feed side of membrane samples collected from feed, middle and concentrate end.

The dye was observed from the permeate side of the membrane. The penetration of the dye indicated structural damage of the membrane; this is probably caused by growth of scale to a thickness exceeding the available space between the membrane leaves thereby prying them apart and tearing into the membrane.

14

Fujiwara Test A sample of the membrane was subjected to a Fujiwara test. A positive reaction indicated halogen damage to the membrane surface. Examples of Halogens are chemicals such as chlorine and bromine. The tests are carried out for samples from feed end, middle and concentrate end of the membrane element. The photos of the test results are insert below and all the tests were carried out with a blank (test tube with colorless solution) for comparison.

Tube A is 100% negative results with blank, tube B is 100% positive results, tube C is the membrane sample which has negative results, tube D is a virgin membrane sample with negative results for comparison. The Fujiwara tests showed no chlorine damage.

15

Foulant and Scalant Collection 1. Record the procedure of collecting foulant and/or scalant.

Large amount of half dry salt deposited on the surface of membrane sleeve and spacer.

2. Appearance of foulant and/or scalant Yellow color dry solids

3. Odor of the foulant and/or scalant No strong odor.

4. Viscosity of foulant The scale is solid and dry and not viscous.

5. Additional notes (attach photos if available) Collected scale did not dissolve in 10% HCl. Neither did it dissolve in 10% NaOH solution. However, it was dissolved in a special cleaning procedure that adopted AWC products that specifically designed to remove CaSO4 scale.

From Left to Right: Left: scale was added in 2%C238 solution at natural pH and 45 degree C. Middle: scale was stirred overnight in the solution and was dispersed by C238. Right: then 2%C239 was added and the pH was adjusted to 12.5, the dispersed scale particles were dissolved.

16

Advanced foulant/scalant analysis

SEM imaging and EDS analysis SEM (Scanning Electronic Microscopy) is used to determine topography, morphology and crystallographic orientation of a sample. The SEM shows very detailed images at magnifications up to 200 thousand times. EDS (Energy Dispersive Spectroscopy) analysis is a standard procedure for identifying and quantifying elemental composition of a sample. The material is bombarded with electrons from a SEM and the X-rays produced are measured by an X-ray dispersive spectrometer. Every element has its own characteristic wavelength and can be identified accordingly. The scale collected from the membrane is examined with SEM and EDS analysis. SEM images and EDS spectrums, together with composition reporting tables are attached in the section.

Minera Yanacocha scale image at 5000X magnification.

17

Minera Yanacocha scale image at 200X magnification.

18

EDS spectrum showed the elementary compositions of the Minera Yanacocha scale. Element Wt % At % C 9.89 18.47 O 37.11 52.01 Na 0.64 0.62 Si 1.84 1.47 S 18.86 13.18 Pd 2.06 0.43 Ca 22.98 12.86 Fe 0.71 0.29 Au 5.9 0.67 Total 100 100

The quantitative ratio of the elements in the scale The scale is mainly CaSO4 with small amount of Si and Fe.

19

FTIR analysis Fourier Transform Infrared spectrometer (FTIR) is a powerful tool for identifying types of chemical bonds (functional groups). The wavelength of light absorbed is characteristic of the chemical bond. The spectrum of an unknown material can be identified by comparison to a library of known compounds. FTIR test is carried out for the scale after it was dried at 80 degree C for 3 hours. FTIR analysis indicates functionality associated with a hydrated metal salt or oxide exclusively. The sample is therefore likely mainly a hydrated calcium and sulfur salt. The spectrum is shown below:

FTIR spectrum of scale dried at 80 degree C for 3 hours.

FTIR spectrum of a CaSO4 standard

4000.0 3000 2000 1500 1000 600.015.820 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

100.0

cm-1

%T 3391.76

2209.35

1681.91

1617.87

1425.47

1097.26

666.31

4000 6503500 3000 2500 2000 1500 1000

101

25 30

40

50

60

70

80

90

cm-1

%T

20

Results Discussion The customer of Minera Yanacocha had a very severe membrane scaling problem. The membrane was autopsied at AWC and the composition of the scale was identified.

Findings and discussion The scale was mainly CaSO4. The scale had grown so severely that the membrane sleeves had been damaged mechanically as shown in dye testing. This particular membrane element was scaled and damaged beyond the limits of repair. The cause of CaSO4 scale growth was that the antiscalant in use was not able to control the formation of CaSO4 scale. Tube testing in the lab of AWC antiscalants showed successful control of CaSO4 scale when dosed as recommended in the antiscalant projection program.

Conclusion and recommendation The tested membrane was severely scaled and damaged. If the membrane elements were scaled to such extend, it should be replaced with new membrane elements. To clean the elements with less scale and damage, combination of AWC C238 and C239 can be an efficient method. For future operation, acid should be added to reduce LSI - due to the excessively high feed pH of the system, it is not possible to operate without acid dosing. AWC antiscalant A104 should be used to control CaCO3 and CaSO4 scale formation for the RO system. Reviewed by Mohannad Malki Technical Director

21

Release of Liability The Membrane Autopsy Service (The Service) was performed in accordance with the standards of care, skill, and diligence normally provided by a professional in the performance of similar services. American Water Chemicals, Inc. makes no warranty of any kind with the respect to The Service and will not be liable for any damages resulting from the use or misuse of The Service. In no event shall American Water Chemicals, Inc. have any liability for The Service, including, but not limited to, special, indirect, incidental, consequential, or other direct damages whether such liability arises in contract, negligence, strict liability, or otherwise, and the Client hereby agrees to release and indemnify American Water Chemicals, Inc. against same.

22

Attachment AWC antiscalant projection program report:

23