Mineral Ballast Sten Område 2 Rapport nr 2.2.5:1

Transkript

1 MinBaS II Mineral Ballast Sten Område 2 Rapport nr 2.2.5:1 MinBaS II område nr 2 Produktutveckling Delområde nr 2 Utveckling av industrimineralbaserade produkter Projekt/Delprojektnamn nr Coating och malning av industrimineral med Hicom-teknik Slutrapport Malning och coating med Hicom-teknik Eric Forssberg, MISEC AB Stockholm i april 2011

2 Sammanfattning Vid besök hos Hicom- hos Ludovici Australia Pty, Pinkenba, QLD, Australien i oktober 2009 diskuterades torrmalning och coating av industrimineral. Ett projekt med två försöksmaterial genomfördes. Som försöksmaterial användes kalksten med deltagande av Nordkalk AB och Omya AB. Försöken genomfördes hos Ludovici i deras försöksanläggning med en Hicom 25 kw utrustad med vindsikt Comex ACX 200. Försök gjordes med tillsats av stearat som coating kemikalie. Försöken gjordes andra halvåret Materialprover har tillställts de deltagande företagen för analysering och utvärdering som ännu ej är färdig och som kommer att redovisas senare. För malning och coating ner till 3 à 4 micron fås i en Hicom om 110 kw en kapacitet av något ton per timme. Summary Coating and grinding of industrial minerals was discussed with Hicom at Ludovici Australia Pty, Pinkenba, QLD, Australia in October In this project limestone from Nordkalk AB and Omya AB was used for tests with coating and grinding during the second half of Samples have been sent to the participating companies for evaluation. The results from the evaluation are not yet available and they will be reported later outside the MinBaS framework. A capacity of about one ton per hour is obtained in coating and grinding to 3 à 4 micron in a Hicom of 110 kw.

3 Innehållsförteckning - MinBaS proj Sammanfattning Summary Rapport Bilaga 1. Besök Hicom den Bilaga 2. Projektförslag. Coating och malning av industrimineral med Hicomteknik, Bilaga 3. Hicom pilot plant description Bilaga 4. Confidential report H MIS.01. Hicom pilot plant dry grinding trials on Calcium Carbonate for Misec. Nordkalk PArfill 7 results. 16 September 2010 Bilaga 5.. Confidential report H MIS.02. Hicom pilot plant dry grinding trials on Calcium carbonate for Misec AB. Omyacarb 10 results. 25 January 2011.

4 MinBaS Projekt Coating och malning av industrimineral med Hicom-teknik. 1. Inledning. Hicom-tekniken har utvecklats under lång tid. Från början var fokus på våtmalning oh ett omfattande utvecklingsarbete genomfördes i Australien. Bland kända tillämpningar kan nämnas frimalning av diamanter vid off-shore utvinning. Jag fick första gången kännedom om Hicom tekniken år 1985 och besökte senare MD Research utanför Sydney, NSW. I oktober 2009 besökte jag Ludowici Australia, Pty i Pinkenbaa utanför Brisbane, QLD. Reserapporten finns som bilaga #1. Teknologin hade flyttats och inriktningen var nu på torrmalning och en kombination med coating för ytbehandling av fyllmedel för termoplast. På grundval av erfarenheterna från besöket och efter kontakter med företagen utarbetades ett projektförslag för MinBaS område 2. Detta projektförslag, bilaga # 2 godkändes av styrgruppen och ett slutligt avtal tecknades den Två av MinBaS medlemsföretag visade intresse för att deltaga i försöken hos Ludowci i Brisbane. Detta var Nordkalk och Omya. Försöksmaterial, Parfill 7 skickades från Nordkalk till Brisbane. För Omya anskaffades försöksmaterial, Omyacarb 10 lokalt i Australien. Efter undertecknande av sekretessförbindelser beslöts att försöken skulle genomföras under vecka 31, 2-6 augusti Per korrespondens hade erforderlig tid för försöken diskuterats och en vecka bedömdes som tillräckligt för två material. Malningsförsök skulle genomföras med och utan coating. Försöksanläggningen för Hicom hos Ludowici är påkostad och beskrivs i bilaga # 3. I princip består anläggningen av en Hicom kvarn storlek 25 kw och en vindsikt typ COMEX ACX 200. I övrigt finns utrustning för pneumatisk transport, dammavskiljning, provtagning och en Insitec partikelstorleksanalysator. För matning av stearinsyra finns utrustning för smältning och pumpning. Styrsystem och datainsamlingssystem kompletterar utrustningen. 2. Försökens genomförande och resultat. Det stod klart på ett tidigt stadium att försöken inte skulle kunna genomföras under vecka Praktiskta problem uppträdde med materialhantering och matning av stearinsyra. Den ledning som skulle föra smält stearinsyra till kvarnen var inte tillräckligt isolerad varvid materialet stelnade och blockerade ledningen. Ett litet antal försök med Parfill 7 hanns med under vecka 31 och resten av försöken genomfördes under hösten Jag fick tillfälle att besöka Brisbane ytterligare en

5 gång under perioden 6-10 september 2010 för deltagande i XXV International Mineral Processing Congress, IMPC. Jag besökte då Ludowici en gång för att diskutera försöken inom MinBaS med Dr Steve Marshall och ytterligare en gång tillsammans med Dr Andreas Fredriksson från LKAB, på den tiden representerande Minelco. Andreas Fredriksson hade tidigare visat intresse för att deltaga i MinBaS försök men av olika anledningar hade detta ej blivit av. En rapport över försöken med Parfill 7 erhölls i slutet av september 2010, bilaga # 4. En rapport över försöken med Omyacarb 10, bilaga # 5 erhölls i slutet av januari Försöksresultaten har kommenterats i bilagorna # 4 och 5. Försöksresultaten visar att det är svårt att mala utan malhjälpmedel och att det är möjligt att komma ner till till 97 % mindre än 3 à 4 micron. För en fullstor anläggning skulle kapaciteten för en Hicomkvarn om 110 kw bli något ton per timme. Det rekommenderas att två Hicom kvarnar kombineras med en vindsikt. 3. Fortsatt arbete. Ett stort antal prover från malning med såväl Omyacarb 10 som Parfill 7 har skickats till Omya respektive Nordkalk för utvärdering som fyllmedel för termoplast. Några resultat från dessa utvärderingar föreligger ej ännu. En separat rapport kommer att presenteras senare. MinBas har betalat Ludowici cirka kronor för försöken. Ludowicis egeninsats uppgår till cirka kronor. Åkersberga den Eric Forssberg Misec AB

6 Besök Hicom den , Ludowici Australia Pty, Ltd.,Pinkenba, QLd (Brisbane) Kontakt:,Dr Steve Marshall, manager Hicom technologies, Hicom är sedan kort tid en del av Ludowici. Ludowici tillverkar diverse utrustning för mineralberedning som vibrationssiktar och avvattningscentrifuger. Andra intressanta områden är slitbeläggningar av kalcinerad bauxit med resin och keramiska plattor som klistras. För slitbeläggningar i rörledningar rullas slitmaterial och resin inne i röret. Ludowici gör också polyuretan detaljer för t ex siktar. I Brisbane sker montering och målning. Maskinbearbetning sker huvudsakligen genom lego eller t ex i Indien. Försöksanläggningen för Hicom har flyttats från Sydney till Brisbane i slutet av Steve Marshall var den enda som kom med. Han anser att man nu har en mer kommersiell verksamhet jämfört med då R&D finansierades av Charles Warman. Det ultimata syftet för Charles Warman var att skapa en utrutning med hög energitäthet som kunde användas under jord för frontnära malning. Tidigare låg fokus på våtmalning t ex för diamanter i marine deposits. Där gällde det att mala ner snäckskal som spred röntgenstrålning på ungefär samma sätt som diamanter och följaktligen förhindrade XRF sorting. En annan fördel med Hicom var att den genom de små dimensionerna kunde placeras ombord på fartyg. Nu är fokus på torrmalning av Industrial minerals. En typisk anläggning består av 2 stycken Hicom om 110 kw, vilket är maxstorleken och en vindsikt. Vindsiktarna kan vara dels Comex, dels Hosokawa. Pilotanläggningen i Brisbane är uppställd med en Comex vindsikt. Man vill leverera hela anläggningar med Hicom, transportutrustning steel work, styrsystem och vindsikt. Pilotanläggningen har för övrigt en Insitec partikelanalysator on line. Tidigare användes rubber lining i Hicom men denna höll inte länge i våtmalning förmodligen på grund av de höga krafterna och den höga temperaturen. Kylning av varmt gods på grund av den höga energiintensiteten är fortfarande ett problem. Steve Marshall visade hur man genom att ta upp ett hål i manteln kunde kyla effektivt. En annan möjlighet att kyla materialet är att tillföra vatten men det är ej så praktiskt. Typiska temperaturer kan vara 90 grader C. Nu användes steel lining bestående av white iron, (gjutjärn) och det går bra även för abrasiva material som SiC. En steel lining kan räcka ett år jämfört med gummi kanske en månad. Steve Marshall anser att man nu kommit över olika mekaniska problem som tidigare förekom. För att abrasion inte skall vara något problem krävs att ingående inte är för grovt. Ett ingående om cirka 50 mikron går bra. Vore det 1 mm skulle det blir slitageproblem. En målsättning enligt Steve Marshall nu är att marknadsföra Hicom som ett system för malning och coating av fyllmedel för plast. Med två Hicom och en klasserare torde man kunna producera 2* 750 kg coatad filler, t ex CaCO3 per timme för termoplast. Energiförbrukningen blir lägre än för den nu använda tekniken med våtmalning, torkning och coating. Investeringskostnaden för en sådan anläggning blir ungefär MAUD 2 komplett. En

7 Hicom svarar för AUD Däremot måste sägas att Hicom bara för malning inte är särskilt energieffektiv. Coating med steric acid. Denna finns i en behållare som värms så att stearinsyran smälter och sedan användes en pump för att spraya kemikalien. Ungefär 10 Hicom anläggningar är i drift. Exempel på material är: Zirkon Kiselkarbid Talk CaCO3 Silika Mica Baryt Fly ash Kaolin Diamantmalm För t ex Zirkon är det möjligt att uppnå D97 2,4 mikron och för CaCO3 D97 = 3.5 mikron. För torrmalning utan coatingsyfte måste oftast grinding aids i form av tex EDTA tillsättas, kemikalier väljs efter vilket mineral som skall malas. Det finns sedan rätt länge en Hicom hos Sintef i Trondheim. För ett MinBas projekt är det mer ändamålsenligt att göra försöken i Brisbane. Som malmedia kan material ner till 1 mm användas. Normalt är dock 2,5 mm. Vanligen användes yttriumstabiliserad zirkoniumoxid eller stål. Aluminiumoxid blir för sprött och slås sönder snabbt vid den höga impacten. Media kostar storleksordningen USD 40 per kg. Detta kan verka högt men det går inte åt mer än 170 kg media för hela chargen i en 110 kw maskin. Styrning av malfinlek sker genom: Uppehållstid Öppen utmatningsyta Mediastorlek Fyller man Hicom med mer media blir det snarare fråga om skrubbning än om malning. Vad som verkligen sker inne i Hicom vet man inte så mycket om. Det finns DEM modeller och PBM.

8 CSIRO har gjort CFD simuleringar som visar kulornas rörelser. Vid t ex malning av mica och kaolin fås förmodligen en viss delaminering men det är osäkert. För kaolin fås en bättre liberation och därmed ökat utbyte. Andra material som skulle kunna vara intressanta för ett MinBaS projekt vore magnetit. För försök med pilotanläggning får man räkna med 1 à 2 ton material och upp till fyra dagars arbete. Kostnaden är AUD 2000 per dag men då ingår även rapport. Steve Marshall skall skicka en hel del material på CD: Presentation Technical data Particle size distribution Movies Pictures Steve Marshall skall göra en round the world trip I februari/mars 2010 och besöker då gärna intresserade företag. File name Hicom

9 HICOM Projektförslag Coating och malning av industrimineral med Hicom-teknik. 1. Inledning Hicomtekniken utvecklades på 1980-talet. Målsättningen var att ta fram teknik för malning med hög energiintensitet. Hicom karakteriseras av att malningen sker i en behållare fylld med malkroppar och att denna är upphäng och utför en nuterande rörelse. Utvecklingsarbetet bedrevs i stor skala i Sydney, NSWoch finansierades av Charles Warman. (Warman pumps). Ett litet antal Hicom-anläggningar såldes framför allt för våtmalning av marina diamantförande material. Hicom teknologin har 2008 övertagits av Ludowici Australia Pty. Ltd med anläggningar i Brisbane, Australien. En ny försöksanläggning har satts upp och focus har ändrats från våtmalning till torr malning och behandling. En mycket intressant applikation är coating och malning av industrimineral. Ytterligare information framgår av Eric Forssbergs rapport från besök den Ett projekt föreslås omfattande coating och malning av ett à två utvalda industrimineral vid Hicoms anläggning i Brisbane. Proverna skickas tillbaka till de deltagande företagen för utvärdering och en sammanfattande rapport utarbetas. 2. Målsättning. Målsättningen med det föreslagna projektet är att utvärdera och bedöma Hicomteknikens potential för malning och coating av filler. 3. Projektets genomförande. Projektet genomföres av Eric Forssberg, Misec AB. Projektet omfattar följande moment: 1. Val av försöksmaterial i samråd med deltagande företag à 1000 kg försöksmaterial, mindre än 50 micron skickas till Hicom i Brisbane 3. Försök med coating och malning vid Hicom i Brisbane. Partikelstorleksfördelning bestämmes med befintlig Insitec-utrustning. Försöksparamterar är uppehållstid, avskiljningsgräns för vindsikt, typ COMEX, mediastorlek, öppen utmatningsyta, koncentration av coatingkemikalie. Energiförbrukningen bestäms. 4. Prover tas ut och skickas för undersökning hos deltagande företag.

10 5. Sammanställning av försöksresultat och värdering av tekniken dels med avseende på malning, dels för coating och produktutveckling av filler. 4. Kostnader för projektets genomförande. Projektet beräknas kunna genomföras inom en kostnadsram av kronor Enligt nedanstående specifikation. 1. Uttag av prover, analysering och frakt till Brisbane, naturainsats Kostnad för försök vid Hicom AUD 10000, kontant Rese- och uppehållskostnader, kontant Analysering av prover vid deltagande företag, naturainsats Arbetskostnad för Eric Forssberg, kontant Arbetskostnad för Eric Forssberg, naturainsats Summa projektkostnad Kontant Naturainsats Tidplan Projektet beräknas kunna genomföras under tiden Hicom projförslag

11 Hicom pilot plant Description Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 1 of 10

12 Contents Hicom 25 Dry Pilot Plant: Description and Operating Procedures... 3 Typical Test Procedure... 4 Grinding circuit behavior and sampling... 6 Data Analysis Procedures... 8 Test conditions... 8 Feed and product rate... 8 Circulating load ratio estimation Author: Dr. Steve Marshall Report Date: 23 rd May 2010 Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 2 of 10

13 Hicom 25 Dry Pilot Plant: Description and Operating Procedures Figure 1 Photograph showing the Hicom 25 dry pilot plant The Hicom 25 dry pilot plant is shown in the above picturae (Figure 1) Figure 1and schematically in Figure 2 below. The plant consists of a Hicom 25 kw mill with variable speed drive, operating in closed circuit with a Comex ACX200 high efficiency air classifier. The entire plant is controlled and monitored using a Siemens S7-300 PLC and Siemens WinCC SCADA package operating on a touchpanel PC mounted in the main control cabinet. A 75 mm screw feeder is used to transport material to the mill from a feed bin. Solids feed rate to the mill is calculated from loss-in-weight measurement from a load cell on the feed hopper. The calculated rate can be used in closed loop with the screw feeder VSD to provide feed rate control. The Hicom 25 mill motor is controlled by a Siemens VSD in the main control cabinet. The mill is generally operated at discrete speeds of 760 and 960 RPM corresponding to maximum chamber acceleration of 30 and 50 G respectively. The mill drive lubrication system is monitored and controlled by the central Siemens PLC. The grinding system operates under vacuum in order to avoid dust emission. Material is drawn through the mill and pneumatically conveyed to the classifier. The air flow required for effective pneumatic transport through the mill is much less than that required for effective classification. Therefore, additional air is drawn into the system through the primary air valve indicated on Figure A1.1. The setting of this valve and the secondary air valve also control the differential pressure across the mill that is the mill vacuum. Oversize particles, rejected by the classifier rotor, fall by gravity down the oversize chute for regrinding in the mill. The classifier is operated by a VSD which allows the rotor speed to be set to achieve a precise product top cut size. Compressed air is used to seal both the classifier rotor and the Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 3 of 10

14 rotor bearings. The classifier oversize return is sealed by a 150 mm double-butterfly valve air lock system as indicated on the diagram. The secondary air flow to the classifier is manually adjusted by a butterfly valve, and monitored by an orifice-plate flow meter. Air and fine product are pneumatically transported to a Torit-DCE DLM V20/12B Dalamatic dust collector where the product is collected in a drum or bulker bag. The dust collector is sealed by a 200 mm double-butterfly valve air lock system. An Insitec on-line particle size analyser is installed on the classifier fine-product line. This enables instant feedback on classifier performance and provides the means for meeting precise particle size specifications by automatic adjustment of classifier rotor speed. Two blowers operated in parallel are used to generate the system air flow. A Rietschle SAP1500 (System Blower 2) is run at full speed, and a GAST R93150A (System Blower 1) is operated by a VSD to provide trim control on system air flowrate in closed-loop feedback with an orifice-plate flow meter downstream of the dust collector. The total system air capability is roughly 1600 m 3 /hr at - 20 kpa using both blowers. Instrumentation is incorporated for monitoring critical process and mill control parameters, most of which are recorded on the SCADA system. The mill power draw is determined from direct reading of the Mill VSD. A microwave mass-flow indicator installed on the classifier feed (mill discharge) line provides feedback as to whether the plant is at steady state. The grinding chamber nominal volume is 10.7 L and its 40 mm discharge ports are positioned at the circle of maximum diameter. Grates are placed over the discharge ports to retain the media inside the grinding chamber. The grate slot width is generally selected at least one-half the diameter of the smallest media particle used. Typical Test Procedure After every chamber change-out, or after an extended shutdown, the mill is operated for twenty minutes with an empty chamber to establish the no-load power. The required charge of media is added to the mill before commencing each test. The solids feed rate to the mill is selected, and the system and secondary air flows set to maintain appropriate classifier conditions. The classifier rotor speed is then adjusted to give the desired cut size based on Insitec particle size readings. Product and recycle samples are taken once relatively steady-state plant operation is obtained, as indicated by the mill discharge mass flow indicator. This is generally 20 to 25 minutes after starting a run. Critical mill control and process parameters are monitored during each run and recorded on a standard log sheet every time a sample is taken. The recirculating load rate is estimated after taking a physical sample of the mill discharge after a crash stop of the plant. The particle size distributions of the classifier feed, fine product and coarse reject streams can be used to back-calculate the recirculating load ratio. The rate of product discharge from the dust collector is calculated from gain-in-weight measurement of the product bulk bag, which is positioned on electronic weigh-scales. Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 4 of 10

15 100 NB 100 NB 200 NB CONFIDENTIAL FT F IC FI IN SITEC PI IA VSD M PI D UST C OL LEC TOR FI FT COM MEX ACX 200 CLASSIFIER 15 0 NB PI PI PI M VSD JT JI LOAD C ELL SY STE M BL OW E R 1 FI FT FEED H OPPER W F IC VSD M SE C ON DA R Y A IR V ALV E PI FIN E PR OD U C T C OL LEC TI ON FI JI JT VSD M PI PT TS TI H ICOM 25 MIL L PE BB LE TR AP PR IM A RY A IR V ALV E Figure 2 Schematic diagram of the Hicom 25 dry pilot plant Hicom Report PE-0816.P-1 (Revision 1) 23-May-2010 Page 5 of 10

16 This rate is compared with the feed rate to assess whether the circuit is at steady state. Generally, the feed and measured product rates must be within 20% of one another, otherwise the data is from the run is not considered for analysis. The exception to this rule is when the material is very fine or sticky and there is significant holdup of material in the dust collector. Under such conditions, accurate determination of product rate is not possible over a short time period, and we rely on microwave sensor readings of the circulating load to determine if the plant is at steady state. The mill net power draw for calculation of specific mill grinding energy is determined as the difference between the measured gross power and the no-load power. Grinding circuit behavior and sampling Typical circuit responses for dry pilot plant operation and the test protocol followed are best illustrated with reference to Figure 3 below, which shows a characteristic SCADA trend obtained during a pilot plant trial. Figure 3 Hicom 25 pilot plant SCADA Trend screen Between 5:54 pm and 6:10 pm, the mill power draw (red trace) was around 11 kw, the circulating load (black trace) was below 10% and the mill exit temperature (light blue trace) was around 72 o C. Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 6 of 10

17 The feed rate (oscillating blue trace) was increased slightly at around 6:10 pm. This resulted in an increase in circulating load, a decrease in mill power and a decrease in mill temperature due to the increased rate of heat removal from the mill from the higher solids throughput. Despite the increased circulating load, the circuit is nevertheless stable as the circulating load is not increasing above 15-20% on average. This indicated level of circulating load was considered the maximum stable level for plant operation with ATH. Experience showed that further increases in feed rate resulted in accelerating increase in circulating load rate due to the fact that the rate of fresh feed to the mill started to exceed the rate of fine particle production. The objective in pilot plant trials was to adjust conditions such as discharge port open area, mill vacuum, media size and quantity and other factors to try and maximize the mill feed rate before an excessive circulating load rate was reached. In the example shown in Figure 3, at around 6:36 pm, the plant was stopped (crash stop) by stopping the mill, air blowers, the classifier and by shutting the classifier return air lock valves. This way, a snap shot was taken of the circuit from which samples could be taken for analysis. We sampled the recycle stream, the residual powder on the internal walls of the mill body (equivalent to classifier feed) and also the fine product collected in the product filter. These samples were used to estimate recirculating load ratio, as outlined in Appendix B. For some runs, the mill contents were also removed and the powder and grinding media separated by screening. This way it was possible to determine the holdup level of powder in the mill and also to assess media wear. Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 7 of 10

18 Data Analysis Procedures Test conditions All of the data logged on the SCADA system is collated into an Excel spreadsheet. Where necessary, a simple first order filter can be applied to smooth the data for more accurate estimation of parameter values at the time of sample collection or crash stop. Feed and product rate For most test runs, estimation of feed and product rate is done by calculating the numerical derivative of the recorded change in weight of the feed hopper and the product weigh scales respectively. First-order filtering before and after numerical differentiation is used to reduce the affect of inherent noise in the data. Generally, the feed rate data is considered more reliable as hold up of material in the product filter meant that the change of measured product weight with time is usually not a smooth progression. An algorithm was introduced into the PLC program to calculate the feed rate in real time. However, because of the long lag times necessary to achieve a smooth output, and a periodic variation in screw feeder output, use of this calculated rate to control the screw feeder can cause oscillation in the controlled feed rate. It is noted that these oscillations do not significantly affect process operation as they are usually dampened by the relatively high circulating load in the grinding and classification circuit. Typical rate calculation results are illustrated in Figure 4 below. Figure 5 shows the corresponding process parameters of mill air temperature (discharge temperature), mill power and circulating load corresponding to the same time period of the data in Figure 3 and Figure 4. In this example, it can be seen that a relatively small increase in average feed rate from around 58 kg/h to around 62 kg/h resulted in a significant increase in circuit load and it was concluded that further increase was not possible beyond around 62 kg/h for this particular mill and plant configuration. Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 8 of 10

19 RATE (kg/h) WT (kg) CONFIDENTIAL Calculated Feed rate (filtered) Feed rate (PLC output) Feed Hopper Weight (raw) Feed Hopper Weight (filtered) /03/ :00 19/03/ :00 19/03/ : Figure 4 Hicom 25 pilot plant feed rate estimation example Air Temp Mill Power Circulating Load /03/ :00 19/03/ :00 19/03/ :00 Figure 5 Process parameters corresponding to the time periods shown in Figure 3 and Figure 4 Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 9 of 10

20 % Undersize CONFIDENTIAL Circulating load ratio estimation The circulating load ratio, hence coarse recycle rate, can be estimated from the particle size distribution of samples of classifier feed, fine product and coarse reject. The Excel solver function is used to minimize the sum of squares of the difference between measured particles size distribution and the corresponding particle size distribution calculated using an assumed ratio and the other two distributions. Generally, the measured classifier feed is considered the least accurate of the collected samples and this is then taken as the basis for the estimation procedure. In the example shown in Figure 6 below, it can be seen the calculated and measured classifier feed distribution closely match, which gives a high level of confidence in the ratio of 6.6 calculated for this particular test run. Calculation of the ratio using the coarse return and the fine product was also done to verify accuracy of the primary estimate. In most cases, variation in calculated values was less than 10%. The coarse recycle rate was then obtained by multiplying the steady state feed rate by the estimated recirculating load ratio. For those trial runs where no crash-stop samples were collected, the ratio may be estimated from the recirculating load level indicated on the microwave sensor output. Such estimates are considered accurate only within 20%. 100 Measured classifier feed Measured coarse reject Calculated Classifier Feed Measured fine product Size (µm) Figure 6 Results from estimation of recirculation load ratio (RLR) using sum of squares error (SSE) minimization on adjustment of the calculated classifier feed particle size distribution Hicom_Pilot_Plant_Description[2] 23-May-2010 Page 10 of 10

21 Confidential Report H-2010.MIS.01 Hicom pilot plant dry grinding trials on Calcium Carbonate for MISEC: Nordkalk Parfill 7 results H-2010.MIS.01 R0 16-September-2010 Page 1 of 28

22 Contents Executive Summary for MISEC Introduction Objectives Conclusions & Recommendations Equipment and procedures Hicom 25 pilot plant Sample / run labelling Particle Size Measurement Data analysis Test results & discussion Feed material particle size distribution Pilot plant results Product size 3-4 µm (P97)- Table Product size 5-6 µm (P97)- Table Product size 8-9 µm (P97)- Table Product size versus specific grinding energy Scale-up and Hicom 110 production capacity Comments on production plant design Appendix A Hicom 25 Dry Pilot Plant: Generic Description and Operating Procedures Generic Description of the plant Stearic acid dosing system Typical test procedure Grinding circuit behaviour and sampling Appendix B Data Analysis Procedures Test conditions Feed and product rate Circulating load ratio estimation Figures Figure 1 Nordkalk Parfill 7 feed size distribution compared with customer standard... 8 Figure 2 Example of changing product size with change in classifier solids loading H-2010.MIS.01 R0 16-September-2010 Page 2 of 28

23 Figure 3 Product size distributions from the finest uncoated (Run 2) and coated (Run 3) product samples Figure 4 Example of product size control by automatic regulation of classifier speed Figure 5 PSD for intermediate coated product (Run 6) Figure 6 PSD for coarse coated product (Run 9) Figure 7 Product size as a function of specific grinding energy all data Figure 8 Projected Hicom 110 kw production rate as a function of product size Figure 9 Photograph showing the Hicom 25 dry pilot plant Figure 10 Schematic diagram of the Hicom 25 dry pilot plant Figure 11 Hicom pilot plant stearic acid dosing system reservoir and gear pump Figure 12 Hicom pilot plant stearic acid dosing system controls and dosing line Figure 13 Hicom 25 pilot plant SCADA Trend screen Figure 14 Hicom 25 pilot plant feed rate estimation example Figure 15 Process parameters corresponding to the time periods shown in Figure 13 and Figure Figure 16 Results from estimation of recirculation load ratio (RLR) using sum of squares error (SSE) minimization on adjustment of the calculated classifier feed particle size distribution Tables Table 1 Preferred Hicom mill grinding conditions for Nordkalk Parfill Table 2 Summary of results for production of 3-4 µm material... 9 Table 3 Summary of results for production of 5-6 µm material Table 4 Summary of results for production of 8-9 µm material Author: Dr. Steve Marshall Report Date: 18 th September 2010 Revision No: 0 Comments: Initial release for review by customer H-2010.MIS.01 R0 16-September-2010 Page 3 of 28

24 Executive Summary for MISEC A series of trials was undertaken on Nordkalk Parfill 7 in the Hicom pilot plant to demonstrate the concept of simultaneous grinding of calcium carbonate and coating with stearic acid in the one process. Stable plant operation was achieved for manufacture of a range of coated product sizes and provided a high degree of confidence in scale-up of the concept. Reliable data on product size as a function of specific grinding energy, and projected Hicom 110 kw mill production capacity as a function of product size was obtained and is presented in this report. It is recommended that Nordkalk undertake their own particle size analysis and evaluation of other powder properties on selected bulk samples generated during this test work. H-2010.MIS.01 R0 16-September-2010 Page 4 of 28

25 1 Introduction Hicom was approached by Prof. Eric Forssberg, principal of MISEC with a view to understanding more about current developments on the Hicom mill. During the course of discussions held in our Brisbane facility, it was explained that Hicom had recently developed a method for simultaneous grinding calcium carbonate and coating with stearic acid. Following this initial meeting, Prof. Forssberg garnered interest from Nordkalk and OMYA SE in undertaking test work in the Hicom pilot plant on their specific materials. This was done under the auspices and sponsorship of the MinBas group to evaluate the technical and economic case for using new technology in Scandinavian mineral process plants. It was agreed that the present Hicom test work would be undertaken for MISEC who would be acting on behalf of MinBas. This report is therefore directed to MISEC. The first material received for testing was one metric ton of Nordkalk Parfill 7 calcium carbonate from Finland. As there were no target size requirements or particle properties specified, the first series of tests was undertaken as a generic proof-of-concept exercise to demonstrate the capabilities of the Hicom process. The purpose of this report is to present results from this first series of trials on the Nordkalk material. The participation (and patience) of Prof. Forssberg during the initial stages of testing is gratefully acknowledged. 2 Objectives Specific objectives of the test work were as follows: 1. Determine suitable conditions for processing Parfill 7 in the Hicom Mill. 2. Estimate mill grinding energy and corresponding production capacity for a Hicom 110 kw mill over a range of coated product sizes. 3. Provide test samples for evaluation by Nordkalk. 3 Conclusions & Recommendations 1. Table 1 below outlines the mill grinding conditions established as being suitable for this application Table 1 Preferred Hicom mill grinding conditions for Nordkalk Parfill 7 Feed Parfill 7 D97=74 µm Mill Hicom 25 Pilot Plant Hicom 110 Production Mill Mill speed, rpm Mill filling, vol % Media Mass, kg Media type Ce-TPZ (Zirconox, India) Ce-TPZ (Zirconox, India) Media SG, kg/l Media size, mm mm mm Liners 440C Stainless Steel 15/3 Cr/Mo Cast Iron H-2010.MIS.01 R0 16-September-2010 Page 5 of 28

26 2. Mill grinding energy and production capacity estimates are provided in sections (p. 15) and 5.3 (p. 17) of this report. 3. Bulk product samples (5-15 kg) were collected for all test runs. It is suggested that Nordkalk evaluate properties of selected samples from the best runs from each of the three product size groups evaluated. At this stage evaluation of product samples from Runs 2, 3, 6 and 9 would be recommended. H-2010.MIS.01 R0 16-September-2010 Page 6 of 28

27 4 Equipment and procedures 4.1 Hicom 25 pilot plant The Hicom 25 dry pilot plant employed for this test work is described in detail in Appendix A. The grinding media was Zirconox Ce-TPZ ceramic media (Jyoti, India). Further details of the operating conditions are provided in Section Sample / run labelling Each test run sample is given a number, as detailed in the table below: Sample Number 1st part NOR.P.A.001 Sample Number 2nd Part (example) Description Pilot Plant Tests on Nordkalk Parfill 7 1 st series -F Feed material designation -1AP Run/Sample 1A Product (Classifier Fines) -1AD Run/Sample 1A Mill Discharge (Classifier Feed) -1AR Run/Sample 1A Recycle (Classifier Coarse Reject) This labelling convention relates primarily to spreadsheet data and physical samples where provided. In this report, run numbers are given without the first part prefix. Generally, A and B samples refer to duplicate samples taken at the same run condition. In one case here Run 5 the results for A and B samples taken five minutes apart are included to demonstrate consistency of the data. 4.2 Particle Size Measurement Feed and product sizing were measured by laser diffraction on Hicom s Malvern 2000 Mastersizer (with Hydro 2000MU) under the following conditions: Mineral Type CaCO 3 Particle Refractive Index (Mie) Particle Absorption Index (Mie) 0.1 Dispersant Distilled Water Dispersant RI 1.33 Pump speed 2000 Dispersion method (non-coated) Dry sample into 700 ml distilled water in beaker with 15 ml 0.5% w/v Calgon T. 30s Ultrasonic Irradiation at Level 12 prior to measurement Dispersion method (coated) Dry sample in test tube with 3 drops Nonidet P40, 15 ml 0.5% w/v Calgon T, shake for 30s, soak for 1 hr. Froth killed with IPA, suspension agitated with pipette and pipetted into 700 ml distilled water in beaker. 30s Ultrasonic Irradiation at Level 12 prior to measurement. 4.3 Data analysis Details of the procedures used for analysis of logged data are given in Appendix B. H-2010.MIS.01 R0 16-September-2010 Page 7 of 28

28 5 Test results & discussion 5.1 Feed material particle size distribution The feed particle size distribution (PSD) measured on our Malvern laser size was close to the supplied customer specification, as seen in Figure 1, although the top size may have been slightly coarser than standard. 100 Parfill 7 (Hicom measurement) Parfill 7 (Customer specification) % Undersize Size (µm) Figure 1 Nordkalk Parfill 7 feed size distribution compared with customer standard Please note that there is often a wide discrepancy between Malvern (wet) sizing and Insitec (dry, online) sizing data on the same product material. For the sake of consistency, unless noted otherwise, all particle sizes mentioned in this report refer to the Malvern (wet) sizing data. It is also important to recognise that virtually every size analysis method is likely to produce a different result on the same sample. Therefore, the customer needs to analyse physical samples from these pilot plant trials in order to correlate the data and information presented with their own particular knowledge base. 5.2 Pilot plant results Results from all tests are shown in Table 2, Table 3 and Table 4 below. The tabulated data is grouped by product size and discussed below in terms of these groupings. H-2010.MIS.01 R0 16-September-2010 Page 8 of 28

29 Table 2 Summary of results for production of 3-4 µm material Run Number 01A 02A 03A 12A 3/08/2010 3/08/2010 6/08/ /09/2010 System Performance 12:20 16:40 11:25 16:40 Mill GE based on production rate, kwh/t Feed F97, µm Feed F80, µm Feed F50, µm P97, µm Malvern (wet) product sizing data P90, µm P80, µm P50, µm P97, µm Insitec online (dry) product sizing data P90, µm P80, µm P50, µm Recirculating load Ratio Production rate, kg/h Gross Power Draw, kw Net Mill Power Draw, kw Recirculating load, kg/h ACX 200 Classifier Parameters Classifier speed, rpm System air flow, m 3 /h Secondary air flow, m 3 /h % Secondary Air 33% 33% 34% 34% ACX200 Classifier Mass Balance FEED, kg/h PRODUCT, kg/h RECYCLE, kg/h System Configuration Mill model Hicom 25 Hicom 25 Hicom 25 Hicom 27 Mill speed, rpm Discharge ports 2/6 2/6 2/6 1/6*0.6; 1/6*0.9; 1/2*0.4 Discharge slot width, mm , 0.6, 0.9 Liner material Steel Steel Steel Steel Media Ce-TPZ Ce-TPZ Ce-TPZ Ce-TPZ Media size, mm Media S.G Mill Differential Pressure, mmwg Mill Filling, J% 52% 52% 52% 52% Additive DEG DEG Stearic Acid Stearic Acid Additive rate vs fresh feed (%w/w) Classifier Efficiency Total Fines Mass Recovery 3.2% 5.3% 6.3% 5.3% %Passing P97 in Classifier Feed Classifier P97 8.7% 14.2% 14.7% 12.2% Solids/Air Ratio to Classifier, kg/m H110 Plant Parameters Feed rate, kg/h Recycle rate, kg/h Nominal Recirculating load Ratio Classifier feed rate, kg/h H-2010.MIS.01 R0 16-September-2010 Page 9 of 28

30 Table 3 Summary of results for production of 5-6 µm material Run Number 04A 05A 05B 06A 11A 6/08/ /08/ /08/ /08/2010 2/09/2010 System Performance 17:27 15:25 15:30 14:05 18:50 Mill GE based on production rate, kwh/t Feed F97, µm Feed F80, µm Feed F50, µm P97, µm Malvern (wet) product sizing data P90, µm P80, µm P50, µm P97, µm Insitec online (dry) product sizing data P90, µm P80, µm P50, µm Recirculating load Ratio Production rate, kg/h Gross Power Draw, kw Net Mill Power Draw, kw Recirculating load, kg/h ACX 200 Classifier Parameters Classifier speed, rpm System air flow, m 3 /h Secondary air flow, m 3 /h % Secondary Air 35% 35% 35% 35% 36% ACX200 Classifier Mass Balance FEED, kg/h PRODUCT, kg/h RECYCLE, kg/h System Configuration Mill model Hicom 25 Hicom 25 Hicom 25 Hicom 25 Hicom 26 Mill speed, rpm Discharge ports 2/6 1/6*0.6; 1/6*0.9 1/6*0.6; 1/6*0.9 1/6*0.6; 1/6*0.9 1/6*0.6; 1/6*0.9; 1/2*0.4 Discharge slot width, mm , , , , 0.6, 0.9 Liner material Steel Steel Steel Steel Steel Media Ce-TPZ Ce-TPZ Ce-TPZ Ce-TPZ Ce-TPZ Media size, mm Media S.G Mill Differential Pressure, mmwg Mill Filling, J% 52% 52% 52% 52% 52% Additive Stearic Acid Stearic Acid Stearic Acid Stearic Acid Stearic Acid Additive rate vs fresh feed (%w/w) Classifier Efficiency Total Fines Mass Recovery 11.1% 10.0% 10.0% 11.6% 4.5% %Passing P97 in Classifier Feed Classifier P % 21.3% 10.0% 25.4% 8.9% Solids/Air Ratio to Classifier, kg/m H110 Plant Parameters Feed rate, kg/h Recycle rate, kg/h Nominal Recirculating load Ratio Classifier feed rate, kg/h H-2010.MIS.01 R0 16-September-2010 Page 10 of 28

31 Table 4 Summary of results for production of 8-9 µm material Run Number 07A 08A 09A 10A 31/08/ /08/2010 2/09/2010 2/09/2010 System Performance 16:10 18:00 15:49 17:25 Mill GE based on production rate, kwh/t Feed F97, µm Feed F80, µm Feed F50, µm P97, µm Malvern (wet) product sizing data P90, µm P80, µm P50, µm P97, µm Insitec online (dry) product sizing data P90, µm P80, µm P50, µm Recirculating load Ratio Production rate, kg/h Gross Power Draw, kw Net Mill Power Draw, kw Recirculating load, kg/h ACX 200 Classifier Parameters Classifier speed, rpm System air flow, m 3 /h Secondary air flow, m 3 /h % Secondary Air 35% 35% 35% 36% ACX200 Classifier Mass Balance FEED, kg/h PRODUCT, kg/h RECYCLE, kg/h System Configuration Mill model Hicom 25 Hicom 25 Hicom 25 Hicom 25 Mill speed, rpm Discharge ports 1/6*0.6; 1/6*0.9; 1/2*0.4 1/6*0.6; 1/6*0.9; 1/2*0.4 1/6*0.6; 1/6*0.9; 1/2*0.4 1/6*0.6; 1/6*0.9; 1/2*0.4 Discharge slot width, mm 0.4, 0.6, , 0.6, , 0.6, , 0.6, 0.9 Liner material Steel Steel Steel Steel Media Ce-TPZ Ce-TPZ Ce-TPZ Ce-TPZ Media size, mm Media S.G Mill Differential Pressure, mmwg Mill Filling, J% 52% 52% 52% 52% Additive Stearic Acid Stearic Acid Stearic Acid Stearic Acid Additive rate vs fresh feed (%w/w) Classifier Efficiency Total Fines Mass Recovery 10.0% 8.2% 19.2% 8.3% %Passing P97 in Classifier Feed Classifier P % 13.4% 35.1% 15.2% Solids/Air Ratio to Classifier, kg/m H110 Plant Parameters Feed rate, kg/h Recycle rate, kg/h Nominal Recirculating load Ratio Classifier feed rate, kg/h H-2010.MIS.01 R0 16-September-2010 Page 11 of 28

32 5.2.1 Product size 3-4 µm (P97) - Table 2 This series of test runs was conducted with the classifier rotor speed fixed at 5300 RPM (nominal). While the ACX200 classifier is capable of higher speed (hence finer cut size), the speed used was a conservative value that can be applied for scale up to the larger classifier sizes required for a production plant. The system air rate is obviously an important influence on classifier cut size also. Again, we adopted a conservative approach of using a relatively high system air rate of 800 m 3 /h to ensure reliable material transport in the grinding circuit. This air rate was used for all trials on Parfill 7. In short, the product sizes obtained during these pilot plant trials can be readily achieved in a full scale production plant using Hicom 110 kw mills with a commercially available classifier DEG only runs Runs 1 and 2 were conducted with grinding aid only (diethylene glycol DEG) to demonstrate the system capability without stearic acid coating. This was of relevance as it is well known that in ball mills for example, the grinding energy is greatly increased and hence production capacity is decreased when attempting to grind and coat in the one machine. While the grinding energy in both of these runs was similar, Run 2 conducted using 1.4 mm media had a much lower circulating load compared to Run 1 conducted using mm media. In addition, the product size for Run 2 was slightly lower. From this comparison we concluded that operation using the finer media was more efficient (as expected) and all subsequent runs were conducted using the 1.4 mm media Stearic acid coating runs In going to relatively high levels of stearic acid dosing in Runs 3 and 12, we see that the grinding energy was similar to that obtained with DEG at the same classifier speed. However, the coated product size is slightly higher. The higher product size can be attributed to more effective dispersion of material in the classifier separation zone. It is a known phenomenon of calcium carbonate air classification that as the circulating load increases, the particle top cut decreases even though the classifier rotor speed and system air rate remain unchanged. This phenomenon probably occurs because of a filtering effect of high solids loading in the swirling air in the separation zone just outside the classifier rotor. The effect is quite clearly seen in Figure 2 which reproduces a chart from the Insitec online particle size analyser. The red trace shows laser light transmission level which is inversely proportional to the amount of material in the sampling pipe; higher transmission means lower solids loading. The steady increase in product particle size (black traces) with increase in transmission (decrease in solids loading) can clearly be seen in the chart. H-2010.MIS.01 R0 16-September-2010 Page 12 of 28

33 Figure 2 Example of changing product size with change in classifier solids loading With stearic acid coating, the particles are more dispersed than with DEG alone, which is likely to reduce the solids-loading filtering effect observed with non-coated material. This may partially explain the coarser top cut with coated material at similar circulating loads, classifier speed and system air rate, compared with non-coated material Product size distributions The product size distributions shown in Figure 3 for the finest products made illustrate the difference in classifier performance on coated and uncoated materials. The marked difference in distribution shape as reported by the two measurement methods is also apparent. 100 NOR.P.A.001-2AP Insitec (2A) NOR.P.A.001-3AP Insitec (3A) % Undersize Size (µm) Figure 3 Product size distributions from the finest uncoated (Run 2) and coated (Run 3) product samples H-2010.MIS.01 R0 16-September-2010 Page 13 of 28

34 5.2.2 Product size 5-6 µm (P97) - Table 3 For this series of tests, the Insitec size controller was set to a top cut (D97) of 6 µm nominal. The classifier speed was allowed to vary under automatic control to maintain this cut size. An example of such control can be seen in Figure 4. Classifier Speed D97 (Insitec) D97 Set Point Classifier Rotor Speed (RPM) Size (µm) /08 14:00 12/08 14:30 12/08 15:00 12/08 15:30 12/08 16:00 12/08 16:30 Figure 4 Example of product size control by automatic regulation of classifier speed The product size distribution from Run 6 is shown in Figure 5. In general, the Malvern-measured product size was somewhat lower and more variable than the Insitec-reported size, which is due to the different measurement method and also possibly from variability in product sampling. The data from Runs 4-6 is fairly consistent in terms of product rate. The lowest grinding energy and smallest product size was obtained in Run 6. In Run 11, the discharge open area on the grinding chamber was increased and the process was pushed at a high circulating load. While this resulted in a significantly higher production rate, the specific grinding energy was more or less the same as for Run 6. This result demonstrates one way that production rate can be increased in the Hicom process. H-2010.MIS.01 R0 16-September-2010 Page 14 of 28