Geologian tutkimuskeskus Tutkimusjohtaja, prof. Markku Makela. Suurikuusikon malmin rikastustutkimus Tilaus KET519636,

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2 KEMlANTEKNIIKKA 1(22) Mineraalitekniikka TUTKIMUSSELOSTUS N:O KET Tilaaj a Geologian tutkimuskeskus Tutkimusjohtaja, prof. Markku Makela Tilaus Suurikuusikon malmin rikastustutkimus Tilaus KET519636, Kasittelij at Ryhmapaallikko Jaakko Leppinen, puh Tutkimusprofessori Kari Heiskanen Erikoistutkija Reijo Kalapudas Tutkija Jukka Laukkanen Kohde Suurikuusikon malminayte Huom. Eglanninkielinen abstrakti ja kuvatekstit lisatty raporttiin KET VIT KEMIANTEKNIIKKA Mineraalitekniikka Tutkijankatu OUTOKUMPU Puhvaihde (0 13) 5571 Telekopio (013) faetflretmin.htm

3 ABSTRACT Recovery of gold from the Suurikuusikko ore was studied using grinding, flotation, biooxidation and cyanidation tests. The grinding and flotation studies were carried out at VTT and the biooxidation studies at BRGM in France. The grinding studies showed that (at the final fineness of 14 kwh1t) the ore is medium hard. The suitability of the ore to autogenous grinding was not studied and the wear of the grinding medium was not determined. A sulphide bulk concentrate containing approximately 40 glt gold was obtained by flotation at about 90% recovery. The arsenic content in the concentrate was about 5,5% and the sulphur content about 22% the mass recovery being about 15 %. No particular difficulties occurred in the flotation stage and a normal pulp density could be used. The reagent consumption in the flotation stage was moderate (30glt dithiophosphinate and 150 glt xanthate) and ph was 5. The grinding fineness in the flotation was 80% passing pm representing a total energy consumption of 13-14kWhlt. The graphite present in the ore did not markedly interfere the flotation of gold or sulphide minerals but attempts to selectively float graphite led to significant gold losses. At the ordinary grinding fineness, the cyanidation recovery of gold from the concentrate was lower than 10% indicating that the direct cyanidation is not a potential process option. Gold recovery from the ore was low ( < 17%) after ultrafine grinding (grinding fineness 80% -10 to 2 pm). It was estimated that the energy consumption of ultrafine grinding would be 50 to 250 kwh1t. The respective cyanide consumption for the ultrafine ground ore was 5 to 16 kglt. Due to low gold recovery and high energy and reagent costs the ultrafine grinding is not a potential process option. The biooxidation studies showed that the sulphide minerals can be broken down using suitable bacterial cultures. The degradation kinetics and other leaching characteristics were similar to other corresponding ores. The leaching time was rather long in the laboratory biooxidation tests (about 2 weeks). The calcite present in the concentrate neutralised the acid formed in the biooxidation stage reducing the need of the neutralising agent. After biooxidation, gold recovery of approximately 90% was achieved in direct cyanidation whereas about 95% gold recovery was obtained using Carbon-In-Leach (CIL). Regrinding of the concentrate made the biooxidation faster and increased gold recovery in cyanidation. Cyanide consumption was relatively high per ton of concentrate (5-6 kglt) but only moderate calculated per ton of ore (0,6-0,9 kglt). Lime consumption in the cyanidation was relatively high (10-20 kglt concentrate and 1,s-3 kglt ore) which is mainly due to neutralisation of the acid formed in the biooxidation stage. The mass of the solids was reduced by 30-40% in the biooxidation resulting in high Fe and As concentrations in the solution. Other concentration methods than flotation were not studied but the low gold recovery in direct cyanide leaching does not support e.g. gravity separation process options. Other pretreatment options than biooxidation were not studied. Based on the laboratory-scale testwork, a process flowsheet is proposed for the beneficiation of the Suurikuusikko ore.

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10 continued continued Syotteen laskennalliset rikkikiisu ja arseenikiisupitoisuudet on esitetty taulukossa 2. Kairasydkten osalta laskenta perustui GTK:n analyysien perusteella tehtyyn mineraalikoostumuslaskelmaan (liite 3). Taulukko 2. Suurikuusikon malminaytteen laskennalliset mineraalipitoisuudet Table 2. Calculated mineral composition of the Suurikuusikko ore sample Kairasydihten koostumusanalyysin ja kullan mikroanalyysien perusteella arvioitiin, ett5 kullasta 75 % on arseenikiisussa ja 22 % rikkikiisussa (liite 3) Jauhautuvuus Jauhautuvuustestis~ jauhettiin -1 mm:n raekokoon murskattua 5 kg:n malminaytettii Mergan-kuulamyllylla 25, 40 ja 55 minuutin pituiset jaksot. Syotteelle ja kunkin jauhatusjakson tuotteelle tehtiin seula-analyysit. Lopullinen jauhatushienous 55 min ajalla vastaa suunnilleen vaahdotuskokeissa Eytettya hienoutta. Kutakin jauhatushienoutta (jauhatusaikaa) vastaava energiankulutus (kwh/t ja kwh/t uutta alle 75 pm:n materiaalia) ja Work Index on laskettu jauhatusp6ytikirjassa liitteessii 4, josta poimitut tulokset on esitetty taulukossa 3.

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26 Liite 1/2 ii ' MENETEL~KWAUKSET JA HUOMAUTUKSET _ TILAUSNUMERO: RAPORTOINTIPAIVA: TULOS PATEE VAIN TESTATUILLE NAYTTEILLE. TESTAUSSELOSTEEN SAA KOPIOIDA VAIN KOKONAAN. TESTIT ON SUORITETTU VALISENA AIKANA. VAIN NE TESTIMENETEL~T, JOISSA TASSA SELOSTEESSA ON MERKINTA + MENETELM~~KOODIN EDESSA, KUULWAT AKKREDITOINNIN PIIRIIN. MENETELMA 40 Jauhatus terasjauhinastiassa. MENETELMA 511P Kuningasvesiuutto 90'C:ssa. Analysointi ICP-tekniikalla. MENETELMA 511U Kuningasvesiuutto 90'C:ssa. Analysointi GUS-tekniikalla. MENETELMA 704~ Dokimastinen (fire assay) hajotus- ja rikastusmenetelma 25 g:n naytepunnituksesta. Jalometallien analysointi FAAS-tekniikalla. MENETELMA 810L Naytteen poltto happivirrassa. S:n maaritys IR-detektoinnilla. MENETELMA 811~ Naytteen poltto happivirrassa. C:n maaritys IR-detektoinnilla.

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