The Effect of Acid Leaching on the Recovery of Silver from the Waste Dams of Eti Silver Mining Companies

Abstract

Recently, the silver is traditionally produced with cyanide method. The silver ore taken into production process is sent to solid waste dams after the cyanide leaching. It is known that the silver grade of these wastes is quite high. In this study, it is aimed to increase the silver recovery efficiency from high grade silver in waste dams by making acid leaching. Blended samples taken from the silver ore waste dams belonging to Eti Silver Mining Company (Kütahya) were ground in a crusher, grain size analysis was performed and then sulfuric acid leaching process has been found suitable with the preliminary experiments and pre-activation leaching with different concentrations of sulfuric acid (H2SO4) at 25 °C and 100 °C were applied. Since sodium cyanide (NaCN) will be used in the next stage after this pre-activation process, the pH of the prepared leach solution has been adjusted to the range of 10.50-12.00 range with lime and then NaCN leaching has been carry out. Silver analysis was performed with atomic absorption spectrometry (AAS) at the end of the leaching process and the recovery percent of silver from wastes was calculated. In addition, in order to see the effect of H2SO4 pre-activation process in removing other metals in the samples, metal analyzes were performed with inductively coupled plasma-optic emission spectrometry (ICP-OES) from the solids of the samples in the raw form and then dried samples after leaching with H2SO4 and NaCN. From the results of the analysis, it has been determined that H2SO4 significantly removed the metal pollution. As the concentration of H2SO4 increased, the samples that were removed away from metal impurities showed higher silver recovery yields. As a result of cyanide leaching, it was seen that the yield of silver recovery was increased from 17.6% to 31.7%. It was concluded that increasing the temperature in H2SO4 leaching had no effect on the recovery efficiency and this increase was related to the increase only in the amount of H2SO4.

Keywords

• Recovery of silver
• Sodium cyanide
• Sulfuric acid leaching
• Atomic absorption spectrometry

Eti Gümüş Maden İşletmeleri Atık Barajlarındaki Gümüşün Geri Kazanımına Asit Liçinin Etkisi

Abstract

Günümüzde gümüş üretimi geleneksel olarak siyanür yöntemi kullanılarak gerçekleştirilmektedir. Üretime alınan gümüş cevheri, siyanür liçinden sonra katı atık barajlarına gönderilmektedir. Barajlardaki bu atıkların gümüş tenörünün oldukça yüksek olduğu bilinmektedir. Bu çalışmada, atık barajlarındaki yüksek tenörlü gümüşün geri kazanılmasında asit liçi yapılarak verimin arttırılması hedeflenmiştir. Eti Gümüş Maden İşletmeleri’ne (Kütahya) ait gümüş cevheri atık barajlarından temsili olarak alınan harmanlanmış numuneler çeneli kırıcıda öğütülmüş, tane boyutu analizi yapılmış ve ardından yapılan ön denemelerle sülfirik asit liçi uygun görülmüş ve farklı konsantrasyonlardaki sülfirik asit (H2SO4) çözeltileri ile 25 °C ve 100 °C’de ön aktivasyon liçine tabi tutulmuştur. Bu ön aktivasyon işleminden sonraki aşamada sodyum siyanür (NaCN) kullanılacağı için hazırlanan liçin pH’ı kireç ile 10,50-12,00 aralığına ayarlanmış ve daha sonra NaCN liçi uygulanmıştır. NaCN liçi sonrası atomik absorpsiyon spektrometresi (AAS) ile gümüş tayini yapılarak, atıklardan gümüşün % geri kazanım miktarları hesaplanmıştır. Ayrıca H2SO4 ön aktivasyon işleminin, numunelerdeki diğer metalleri uzaklaştırma etkisini görmek için numunelerin önce ham halde daha sonra H2SO4 ve NaCN liçi sonrası kurutulan katılarından indüktif eşleşmiş plazma-optik emisyon spektrometresi (ICP-OES) ile metal tayinleri yapılmıştır. Analiz sonuçlarından H2SO4’in metal kirliliğini büyük oranda uzaklaştırdığı tespit edilmiştir. H2SO4 çözeltilerinin konsantrasyonu arttıkça metal kirliliklerinden uzaklaşan numunelerin, siyanür liçi sonucunda gümüş kazanım veriminde de %17,6’dan %31,7’ye artış sağlandığı görülmüştür. H2SO4 liçinde sıcaklığın artırılmasının geri kazanım verimine etkisi olmadığı, bu artışın sadece H2SO4 miktarındaki artış ile orantılı olduğu sonucuna varılmıştır.

Keywords

• Gümüşün geri kazanımı
• sodyum siyanür
• sülfürik asit liçi
• atomik absorpsiyon spektrometrisi

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