Küre masif zengin cevherde baz, değerli, nadir metallerin dağılımları ve kazanılması

Abstract

Bu tez kapsamında Küre Aşıköy Açık Ocak İşletmesinden alman Masif Zengin Cevherde, değerli, nadir metal dağılımları incelenmiş ve kazanılma olanakları araştırılmıştır. Çalışmaların Masif Zengin Cevherle sürdürülmesinin sebebleri, sahada rezerv miktarlarını tespit için yapılan jeoistatistik incelemelerde bu tip cevherleşmenin bilinenin aksine daha yüksek miktarda olması ve derinlere inildikçe bu miktarın artmasıdır. Ayrıca, cevher tiplerinin tümünde gerçekleştirilen tam kimyasal analiz sonuçlarında Masif Zengin Cevher en yüksek oranda değerli ve nadir metal içermektedir. Bu çalışmada kullanılan numune % 6.3 Cu, % 0.124 Co, 143 g / t Te, 43 g/t Se, 1.9 g / 1 Au ve 18 g / 1 Ag içermektedir. Mineralojik çalışmalar sonucunda ana cevher mmeraUerinin pirit ve kalkopirit olduğu, ayrıca sfalerit, borait, kovelin, galen ve az miktarda silikat minerallerinin de bulunduğu gözlenmiştir. Kırılmış ve öğütülmüş numunenin boyut dağılımı belirlendikten sonra değişik sürelerde öğütülmüş numuneler ile Hostaflot X 231 kollektör reaktifi ile kademeli flotasyon deneyleri yapılmıştır. Gerek mineralojik gereksede tam kimyasal analiz değerleri ilk kademede düşük, 3. kademede ise en yüksek bakır içeriğine ulaşıldığını göstermektedir. Cevherin oldukça kompleks yapıda olması çok ince boyutlara öğütme gerektirdiğinden 60 dakika sürenin uygun olduğuna karar verilmiştir. Değerli, nadir metal dağılımlarının değişik ürünlerde belirlenmesine yönelik olarak yapılan incelemeler, selenyum, tellür ve altın gibi değerli, nadir metallerin bakır içeriği ile birlikte yükseldiğini, kobaltın ise bakırdan bağımsız olarak gerek verim gerekse tenor açısından flotasyon artığında toplandığım göstermektedir. Yüksek bakır içerikli konsantre üretimi için yapılan deneyler sonucunda en uygun kollektör ve kademe sayılan belirlenmiştir. Cevherin kompleks yapısı sebebi ile iki aşamalı olarak değerlendirilmesi uygun görülmüş, yüksek bakır içerikli flotasyon konsantresi üretimini izleyerek elde edilen flotasyon artığından kimyasal çözündürme yöntemiyle bakır ve kobalt kazanılmıştır. İki aşamalı değerlendirme yöntemi ile bakırın % 95'i ( % 47'si flotasyon konsantresi olarak ) kobaltın ise % 80'ni kazanılmaktadır. Selenyum, tellür ise bakır konsantresinden ve kimyasal çözündürme sırasında baca gazlarından kazanılabilecek, altın ve gümüş ise yine bakır konsantresinden ve kimyasal çözündürme sonrası yapılacak siyanür liçi ile elde edilebilecektir. % 61.6 Fe içeren liç artığının ise demir cevheri olarak kullanımı incelenebilir.

Precious and rare metal industries have increasingly gained importance as new technologies develop all over the world. Because of the demand on special metal alloys used in a number of industrial products ; research and development studies have been conducted with these kind of metals. Extraction of the precious and rare metals more effieciently from ores and concentrates gives way to the production of these metals economically. Selenium is named after Selene - the Greek goddess of the Moon - by the Swedish chemist J. J. Berzelius in 1817. It was discovered in the red residue left after the sulfuric acid treatment of pyrite at the mining operation of Fahlun, Sweden. It associates mainly in the sulphide minerals of copper, iron and lead, most commonly found in chalcopyrite, bornite and pyrite. The principal selenium minerals are berzalianite ( CuaSe ), eucairite ( AgCuSe) and jermoite ( As( S,Se)2 ). It occurs in conjuction with native sulphur and in the form of metal selemdes. Selenium minerals do not occur in sufficient quantities, however the commercial sources of this element are selenium - bearing copper sulphide ores found in Canada, The U. S. A. and The C. I. S. Major uses of selenium include the photocopying process of xerography, which is based on the light sensitivity of thin films of amorphous selenium or iron compounds ; dying agent in plastics, paints, glass, ceramics, and inks. The use of selenium in rectifiers has decreased with the replacement silicon and germanium in this sector. Selenium is also employed in photographic exposure meters and as a metallurgical additive to improve the machinability of certain steels. The properties of tellurium are similar to those of selenium. Tellurium was first isolated by Joseph Franz Müller von Reichestein in 1782. The most IX common minerals of tellurium are sylvanite ( graphic tellurium ), ( Ag,Au)Te2 ; nagyagite ( black tellurium ), ( Ag, Pb )2 ( Te,S,Sb )3 ; hessite, Ag2Te ; tetradymite, Bi2Te3 ; altaite, PbTe ; coloradoite, HgTe and other silver gold tellurides. Like selenium, there are no commercially important deposits of tellurium and it associates with copper, gold, silver and bismuth minerals.Tellurium is generally produced as a by - product from copper production processes. Tellurium is used primarily as an additive to steel to increase its ductility, as a brightener in electroplating baths, as an additive to catalysts for the cracking of petroleum, as a glass colouring agent, and as an additive to lead to increase its strength and corrosion resistance. There are several sources of selenium and tellurium. The commercial sources are copper refinery slimes and flue dusts from copper smelters. The anode muds from electrolytic copper refining account for the most important sources of the unrefined selenium and tellurium containing material, but significant quantities of these elements are found in the sludge formed during sulfuric acid production and found in the electrostatic precipitator dusts accumulated during the processing of certain heavy metals. The aim of this study is to determine, the base, rare and precious metal distributions in the flotation products and recovery possibilities of Kure Massive ores. Previous investigations on Kure pyritic copper ores have reported. The existance of these metals in the ore body, however, no systematical studies have been carried out so far into the evaluation of new processes for the recovery of the rare and precious metals from these ores. There are two reasons why Kure pyritic massive rich ore was choosen in this study. First of all its precious and rare metal contents arecomparatively higher among the other ore formations and secondly the recently completed geostatistical investigation has revealed that the reserve share of the pyritic massive rich ore is larger than suppoised before. The ore sample used in the experimental work, which was taken from Küre Aşıköy open pit mine, assayed 6.3 % Cu, 0. 124 % Co, 143 g /t Te,43 g/t Se, 1.9 g / 1 Au, and 18 g / 1 Ag. The analyses of the rare and precious metals were achieved using X-ray fluoresence method.. The ore sample was below 2 mm by using laboratory type jaw and cone, roll crushers.The minus 2 mm size fraction was subjected to grinding tests at various durations and particle size distributions were determined by screen analysis. Minus 400 mesh material were found as 24.16,51.06, 80.00 and 86.49 % when the samples were ground 10, 20, 40 and 60 minutes respectively. Mineralogical studies of Kure massive rich ore were carrried out with different samples including ore specimens and several flotation products by an ore microscope. The mineralogical studies revealed that chalcopyrite, bornite and kovellite were the major copper minerals and small amounts of sphalerite and galenite were exist in the pyrite matrix. Selective flotation tests were conducted in order to concentrate rare and precious metals in the copper concentrate. Laboratory type conventional Denver flotation cell was used in all the flotation experiments. Collectors employed were Hostafat X 231 ( Hoechst ), Aerophine 3418 - A ( Cynamid ), and Potassium Ethyl Xanthate and Dowfroth 250 was the frother used. The amounts of reagents utilised in flotation experiments were determined according to the their catalogue values. The flotation experiments were carried out using different reagent and at various durations grinding at a constant pH value of 1 1.5 - 12.0. During the flotation tests 5 concentrates were collected at 5 minutes intervals.When Hostaflot, Aerophine and KEX were used as collectors an unusual flotation response of copper minerals were observed where the copper content reached its maximum level at the third stage. Chemical analysis of the flotation products showed that selenium, tellurium, silver and gold contents increased at elevating copper contents, while the cobalt values decreased with increasing copper content. Mineralogical examination of the stage wise flotation products revealed the presence of two different types of pyrite mineral in the ore.One of them is primary pyrite in massive character and other is secondary originated pyrite which is brittle, complex in nature and easily floatable. Mineralogical investigations also showed that 4 fh and 5th concentrates contained mainly unliberated particles even at prollonged grinding durations. Bornite and XI kovellite were observed to accummulate mainly in the 2nd and the 3rd. concentrates. Stage flotation tests and the examination of all products proved that obtaining concentrates with high copper content ( over 20 % ) and acceptable copper recoveries ( over 90 % ) was difficult, because of the complex nature of this ore. Therefore a combined process involving selective copper flotation and hydrometallurgical treatment to recover copper and the rare metals was decided to apply. Flotation tests were carried out with Hostafloat X 231, Aerophine 3418 - A, and KEX as collectors at pH : 11.5 - 12.0 by using laboratory type conventional Denver flotation machine. Rougher concentrates were cleaned once and twice in order to improve the grade of copper concentrates as high as possible. Best results were achieved with one stage cleaning on using Aerophine 3418- A as collector. A copper concentrate with 23.68 % Cu content and 46.92 % recovery was produced containing 33 g/tAg, 5.1g/tAu, 195g/t Te and 87g/tSe. The tailing of this flotation, which was treated by hydrometallurgical processes, also contained 3.88 % Cu and 0. 13 1 % Co. Hydrometallurgical treatment was applied to the flotation tailings after roasting at about 690 ° C in a laboratory type furnace. The roasted materials were leached with water only and with sulphuric acid solutions at 10 g / 1 and 20 g / 1 concentrations. Copper and cobalt were extracted with the recoveries of 91.47 and 82.35 % recpectively on using 20 g / 1 sulphuric acid concentration. In the combined process involving copper flotation and leaching 95 % of the copper could be recovered from massive rich copper ore in Kure deposit. 97 % of Cobalt remained in the flotation tailing and 80 % of Cobalt in the tailing reported to the leach solution. Although selenium and tellurium were enriched in copper concentrates, more than 50 % of these elements were left in the tailing because of the high amount of this product. These metals can be recovered from copper concentrates during metallurgical treatments, from flue dusts and anode slimes. hi the case of tailings, selenium and tellurium are lost mainly in the roasting stage as they volatililize, so they can beecovered from flue dusts in the roasting stage. Gold and silver also concentrated at 5.1 g/t Au and 33g/t Ag levels in copper flotation concentrate. But the xii flotation tailing assaying 1.3 g / t Au and 17 g / t Ag still contained considerable amount of precious metals. After roasting and leaching steps these values were increased to 1.65 g / 1 Au and 20 g / 1 Ag. Precious metals can be recovered by alternative hydrometallurgical treatments from copper and cobalt leaching residue and the remaining residue with 61.6 % Fe content can be used as raw material for iron and steel manufacturing.